Controller for automatic transmission

ABSTRACT

In performing a down-shift based on a driver&#39;s intention of deceleration, an engine output increasing control is started at a time when a transfer torque capacity of the releasing clutch becomes small or zero and the actual oil pressure decreases to an initial oil pressure, not causing an acceleration feeling even upon the engine output increase. For estimating a time when which the real pressure of the releasing clutch decreases to a level of not higher than the initial pressure, the response of the real pressure relative to an oil pressure command value for the releasing clutch is approximated using a transfer characteristic of “first order lag+time delay.” An estimated real oil pressure obtained based on the transfer characteristic is compared with the initial pressure. It is determined a start timing of the engine output increasing control has been reached upon decrease of the estimated pressure to the initial pressure.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/108,891 filed Apr. 19, 2005 which is based on Japanese PatentApplication No. 2004-130644 filed on Apr. 27, 2004, No. 2004-130645filed on Apr. 27, 2004, and No. 2004-134516 filed on Apr. 28, 2004, thedisclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a controller for an automatictransmission involving an improved technique for controlling adown-shift which is executed on the basis of a driver's intention ofdeceleration.

BACKGROUND OF THE INVENTION

Many of the recent automatic transmissions for automobiles are of aconstruction wherein the states of engagement of plural frictionalengaging elements, including hydraulic clutches and brakes, are switchedfrom one to another state by operation of a hydraulic control circuit,whereby plural shift ranges are attained. In an automatic transmissionof such a construction, when a sufficient engine brake force is notobtained even if an accelerator is turned OFF for example on a downhill,a driver turns OFF an overdrive switch or switches a shift lever from DRange to S or L Range to effect a down-shift, thereby increasing theengine brake force.

When a down-shift for increasing the engine brake force is performed onthe basis of a driver's intention of deceleration (e.g., deceleratingoperation) and with the accelerator OFF, the transmission gear ratio ofthe automatic transmission becomes larger as a result of the down-shiftand therefore it is necessary to so much increase the rotational speedof the engine. However, in an operation mode requiring such an enginebrake, the throttle valve is usually closed, so that an output-sidetorque is transmitted to the engine side by the transfer of torquethrough frictional engaging elements which are for attaining a shiftrange after the down-shift, whereby the rotational speed of the engineis increased. Consequently, the time required for the shift becomeslonger and the effect of engine brake may not be obtained at a requiredtiming, or an inertia torque induced with an increase in the rotationalspeed of the engine appears as a braking torque for the vehicle, with aconsequent temporary increase of the engine brake force and generationof a shift shock. Moreover, if the transfer torque of the frictionalengaging elements is suddenly increased for example by a hydrauliccontrol of the automatic transmission, the rotational speed of theengine increases quickly and hence the shift time becomes shorter, butthe braking torque increases rapidly, resulting in the shift shockbecoming more marked.

With a view to solving such problems, a control technique is proposed inJapanese Patent No. 2924463. This control technique uses engine outputincreasing means for increasing an engine output temporarily when anautomatic transmission is shifted down to a lower speed range in whichengine brake acts with an accelerator substantially OFF and a timer formeasuring an elapsed time from a predetermined measurement start pointsuch as, for example, a shift output point at which a hydraulic controlcircuit is switched from one to another state at the time of down-shift.According to this proposed control technique, an engine outputincreasing control by the engine output increasing means is started onthe basis of the elapsed time measured by the timer so that therotational speed of the engine increases after a high speed range-sidefrictional engaging element which is released at the time of down-shiftbegins to slip and until complete engagement of a low speed rangefrictional element which is brought into engagement at the time ofdown-shift. The control start timing is set on the basis of a vehicularoperating condition (more specifically, the temperature of oil in thehydraulic control circuit or the rotational speed of the engine) whichexerts an influence on at least one of engagement/release delay times ofthe frictional engaging elements and an engine output increase delaytime.

In the Japanese patent No. 2924463 it is also disclosed that there is adelay time until actual release or engagement of a frictional engagingelement in an automatic transmission and there also is a delay timeafter a throttle angle control for increasing the engine output has beenperformed and until actual increase of the engine output and thattherefore, by setting the start timing taking those delay times intoaccount, the shift time is shortened while suppressing the occurrence ofa shift shock. Also, according to the disclosure of the patent inquestion, it is preferable to control the degree of opening of athrottle valve so that the engine speed increases in conformity with aslip start timing of the frictional engaging element on the high speedrange side.

In JP-7-247874A, with a view to solving the foregoing problems, there isdisclosed a technique in which, when an automatic transmission isshifted down by manual operation to a low speed range undergoing theaction of engine brake with an accelerator substantially OFF, the amountof intake air is increased and restoring (fuel injection) from fuel cutis performed to increase the engine output. According to this techniquedisclosed in the '874 publication, an ISC valve for idling control isopened to increase the amount of intake air before the shift is startedin the above shift-down, and when the start of the shift is detected bya change in rotation of a rotating member, the supply of fuel is resumedby a fuel cut restoring control to increase the engine torque, therebyshortening the shift time and preventing the occurrence of a shiftshock. In JP-10-18877A there is proposed a technique in which, takingnote of a shift shock diminishing effect by an engine output increasingcontrol in down-shift, a torque increase quantity by the engine outputincreasing control is made larger in an automatic down-shift accordingto a preset shift schedule than in manual down-shift. According to thisproposed technique, in manual down-shift, the torque increase quantityis made relatively small for generating a moderate shift shock whichaffords a deceleration feeling, while in an automatic down-shiftinvolving execution of a shift independently of operation performed by adriver, the torque increase quantity is made relatively large so as notto let the driver feel a shift shock.

However, the delay time until actual release or engagement of theassociated frictional engaging element referred to above at the time ofdown-shift varies depending on not only the temperature of oil in thehydraulic control circuit or the engine speed but also the vehicle speedor the torque acting on the frictional engaging element when thedown-shift control is performed. Particularly, at the time ofdown-shift, since the accelerator pedal is substantially fully closed,it is necessary to take into account that an arbitrary drive torquebelow the road load (below the torque required for constant speedrunning at the speed of the time point concerned) is applied from theengine side. The delay time is also influenced by an operating conditionincluding a slip control for a lock-up clutch being executed. Therefore,in a timer-based setting of a control start time, the throttle valveposition control (engine output increasing control) cannot always bestarted at an appropriate timing even if the influence of the oiltemperature or the engine speed is taken into account. Thus, there is afear that the start timing of the throttle valve position control may beoffset from the appropriate timing and the driver may be given anacceleration or a shock by the throttle valve position control duringdown-shift. Besides, for appropriately setting a reference value of thetimer taking the influence of the oil temperature and engine speed intoaccount, not only it is necessary in a conforming process to set areference value based on repeated experiments but also it is necessaryto again set the timer reference value in the case where there arisesthe necessity of changing the oil pressure removing method due to achange of specification for the hydraulic shift control. Thus, not onlythe logic becomes complicated but also it is necessary to set manyparameters and the parameter conforming work is very troublesome.

Moreover, even if the engine output increasing control is started in aproper manner, an unpleasant shock will be induced if a terminationtiming of the control is not appropriate. For example, in the foregoingdown-shift, if an engagement-side frictional engaging element has asufficient transfer torque capacity and if the engine output increasingcontrol is continued in this state even after the down-shift reaches anearly terminated state, an increased engine output causes the vehicleto be accelerated by a gear on the low speed range side, so that anunpleasant shock as a push-out feeling is developed. Conversely, if theengine output increasing control is terminated in a state in which theengagement-side frictional engaging element does not yet have a transfertorque capacity sufficient for terminating the down-shift, thefrictional engaging element acts in a direction in which the progress ofthe down-shift is decelerated, so that not only the shift time is notshortened, but also a strong deceleration shock is developed by both adecrease of the engine torque resulting from termination of the controland a coast torque applied from the vehicle side.

Further, it is necessary that the engine output quantity increased inthe down-shift be controlled to a proper quantity conforming toconditions. More particularly, in the case where the output increasequantity is excess, not only an excess increase of the engine speedoccurs and an extra time is taken until the end of shift, but also, fordecreasing the increased engine speed by the engaging force of theengagement-side frictional engaging element, a thermal load on thefrictional engaging element increases and there occurs a shift shockbased on inertia energy. On the other hand, in the case where the outputincrease quantity is deficient, there arises the same condition as inthe conventional shift control for increasing the engine speed by theengagement-side frictional engaging element and therefore the inertiatorque consumed for increasing the engine speed cannot sufficientlymitigate the shift shock which is for becoming a vehicle braking torque.Thus, it is necessary that the output increase quantity in the engineoutput increasing control in the down-shift be set and controlled so asto afford a desired engine speed change quantity in the down-shift.

Since the engine output increasing control is performed by an increaseof the intake air quantity and the supply of fuel proportional thereto,not depending on a driver's operation, the application of the samecontrol also to a down-shift based on a predetermined shift scheduletaking into account a slow deceleration such as that in street runningor running on a congested road affords the shift shock diminishingeffect disclosed in JP-10-18877A, but causes the generation of noise dueto a sudden increase of the engine speed and the deterioration of fueleconomy due to an increase of fuel consumption resulting from thiscontrol, and is therefore not advisable.

SUMMARY OF THE INVENTION

The present invention has been accomplished taking the above-mentionedcircumstances into account and it is an object of the present inventionto provide a controller for an automatic transmission which, at the timeof performing a down-shift in accordance with a driver's intention ofdeceleration, can set a start timing of an engine output increasingcontrol with a high accuracy without causing the driver to have anacceleration feeling or feel a shock caused by an engine outputincreasing control and which can execute an engine output increasingcontrol by a simple logic configuration and by the setting of reducedparameters.

It is another object of the present invention to provide a controllerfor an automatic transmission which, at the time of performing adown-shift in accordance with a driver's intention of deceleration, canset a termination timing of an engine output increasing control with ahigh accuracy and which can prevent the occurrence of an unpleasantshock such as a push-out feeling or a deceleration shock at the end ofthe engine output increasing control.

It is another object of the present invention to provide a controllerfor an automatic transmission which, at the time of performing adown-shift in accordance with a driver's intention of deceleration, canexecute a proper quantity of an engine output increasing control inaccordance with vehicular operating conditions.

According to the present invention, in order to achieve theabove-mentioned objects, there is provided a controller for an automatictransmission including engine output increasing control means which,when a shift mechanism is down-shifted in accordance with a driver'sintention of deceleration, executes an engine output increasing controlfor increasing an engine output without depending on an acceleratoroperation by the driver, and also including output increase start timingcontrol means for controlling a start timing of the engine outputincreasing control, wherein the start timing of the engine outputincreasing control is set at a time point when an oil pressure of africtional engaging element which is controlled for release during thedown-shift drops below an oil pressure equivalent to a predeterminedtransfer torque capacity by operation of oil pressure control means.According to this construction, when performing a down-shift inaccordance with the driver's intention of deceleration, the engineoutput increasing control can be started when the oil pressure of thefrictional engaging element which is controlled for release has droppedbelow an oil pressure equivalent to a predetermined transfer torquecapacity not causing an acceleration feeling or a shock even upon startof the engine output increasing control. Consequently, a start timing ofthe engine output increasing control can be set with a high accuracy andthe driver is not given an acceleration feeling or a shock caused by theengine output increasing control. Besides, since a start timing of theengine output increasing control can be set without dependence on such atimer as in Patent Literature 1. Therefore, the engine output increasingcontrol can be executed by a simple logic configuration and by thesetting of reduced parameters. Thus, there accrues an advantage that apractical application is easy.

According to the present invention there is provided a controller for anautomatic transmission including engine output increasing control meanswhich, when a shift mechanism is down-shifted in accordance with adriver's intention of deceleration, executes an engine output increasingcontrol for increasing the engine output without depending on anaccelerator operation by the driver, and also including output increaseend timing control means, wherein when the output increase end timingcontrol means determines that a predetermined state corresponding to asubstantial end of the down-shift has been obtained, it is determinedthat this time point is an end timing of the engine output increasingcontrol. According to this construction, at the time of performing adown-shift in accordance with the driver's intention of deceleration,the engine output can be decreased to a proper value (a value free ofoutput increase) thereof in conformity with a timing at which anengagement-side frictional engaging element comes to have a transfertorque capacity necessary for the completion of the down-shift.Consequently, it is possible to prevent the occurrence of an unpleasantshock such as a push-out feeling or a deceleration shock at the end ofthe engine output increasing control.

Further, according to the present invention there is provided acontroller for an automatic transmission including engine outputincreasing control means which, when a shift mechanism is down-shiftedin accordance with a driver's intention of deceleration, executes anengine output increasing control for increasing an engine output withoutdepending on an accelerator operation by the driver, the engine outputincreasing control means setting an output increase control quantity sothat an engine torque corresponding to a desired engine speed changerate is generated during the engine output increasing control. Accordingto this construction, since an output increase control quantity is setso that an engine torque corresponding to a desired engine speed changerate is generated during the engine output increasing control, theengine torque can be increased by an amount corresponding to an inertiatorque of members (e.g., engine and torque converter) for which isrequired an increase of rotation in the down-shift. Thus, an outputincrease control quantity can always be set neither more nor less and itis possible to solve the foregoing various problems involved in theprior art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic construction diagram of the whole of an enginecontrol system in each of embodiments of the present invention;

FIG. 2 is a diagram showing a schematic construction of the whole of anautomatic transmission;

FIG. 3 is a diagram showing schematically a mechanical construction ofthe automatic transmission;

FIG. 4 is a diagram showing engagement/release combinations of clutchesC0 to C2 and brakes B0, B1 for each of shift ranges;

FIG. 5 is a diagram showing an example of shift patterns;

FIG. 6 is a time chart showing an example of a power ON down-shiftcontrol;

FIG. 7 is a time chart showing an example of an ETC cooperationdown-shift in a first embodiment of the present invention;

FIG. 8 is a flow chart showing a processing flow of a shift controlroutine in the first embodiment;

FIG. 9 is a flow chart showing a processing flow of a shift typedetermination routine in the first embodiment;

FIG. 10 is a flow chart showing a processing flow of a shifting oilpressure control routine in the first embodiment;

FIG. 11 is a flow chart showing a processing flow of a release-sideclutch oil pressure control routine in the first embodiment;

FIG. 12 is a flow chart showing a processing flow of an engagement-sideclutch oil pressure control routine in the first embodiment;

FIG. 13 is a flow chart showing a processing flow of a throttle anglecontrol routine in the first embodiment;

FIG. 14 is a flow chart showing a processing flow of a throttle anglecontrol start determination routine in the first embodiment;

FIG. 15 is a flow chart showing a processing flow of a throttle anglecontrol end determination routine in the first embodiment;

FIG. 16 is a flow chart showing a processing flow of a throttle anglecorrection routine in the first embodiment;

FIGS. 17A and 17B are diagrams each showing an example of a throttleangle setting map in the first embodiment;

FIG. 18 is a flow chart showing a processing flow of a fuel injectionreturn control routine in the first embodiment;

FIG. 19 is a flow chart showing a processing flow of a fuel injectionstart determination routine in the first embodiment;

FIG. 20 is a flow chart showing a processing flow of a fuel injectionend determination routine in the first embodiment;

FIG. 21 is a time chart showing an example of an ETC cooperationdown-shift control in a second embodiment of the present invention;

FIG. 22 is a flow chart showing a processing flow of a shifting oilpressure control routine in a third embodiment of the present invention;

FIG. 23 is a flow chart showing a processing flow of a release-sideclutch oil pressure control routine in the third embodiment;

FIG. 24 is a flow chart showing a processing flow of a throttle anglecontrol start determination routine in the third embodiment;

FIG. 25 is a flow chart showing a processing flow of a timer conditiondetermination (throttle) routine in the third embodiment;

FIG. 26 is a flow chart showing a processing flow of a change in gearratio determination (throttle) routine in the third embodiment;

FIG. 27 is a flow chart showing a processing flow of an initial oilpressure arrival determination (throttle) routine in the thirdembodiment;

FIG. 28 is a flow chart showing a processing flow of a fuel injectionstart determination routine in the third embodiment;

FIG. 29 is a flow chart showing a processing flow of a timer conditiondetermination (fuel) routine in the third embodiment;

FIG. 30 is a flow chart showing a processing flow of a change in gearratio determination (fuel) routine in the third embodiment;

FIG. 31 is a flow chart showing a processing flow of an initial oilpressure arrival determination (fuel) routine in the third embodiment;

FIG. 32 is a time chart showing an example of an ETC cooperationdown-shift in a fourth embodiment of the present invention;

FIG. 33 is a flow chart showing a processing flow of a throttle anglecontrol routine in the fourth embodiment;

FIG. 34 is a time chart showing an example of an ETC cooperationdown-shift control in a fifth embodiment of the present invention;

FIG. 35 is a flow chart showing a processing flow of a throttle anglecontrol start determination routine in the fifth embodiment;

FIG. 36 is a flow chart showing a processing flow of a fuel injectionstart determination routine in the fifth embodiment;

FIG. 37 is a flow chart showing a processing flow of a throttle anglecontrol start determination routine in a sixth embodiment of the presentinvention;

FIG. 38 is a flow chart showing a processing flow of a fuel injectionstart determination routine in the sixth embodiment;

FIG. 39 is a flow chart showing an example of an ETC cooperationdown-shift control in a seventh embodiment of the present invention;

FIG. 40 is a flow chart showing a processing flow of a throttle anglecontrol end determination routine in the seventh embodiment;

FIG. 41 is a flow chart showing a processing flow of a fuel injectionend determination routine in the seventh embodiment;

FIG. 42 is a flow chart showing a processing flow of a throttle anglecontrol end determination routine in an eighth embodiment of the presentinvention;

FIG. 43 is a flow chart showing a processing flow of a fuel injectionend determination routine in the eighth embodiment;

FIG. 44 is a time chart showing an example of an ETC cooperationdown-shift control in a ninth embodiment of the present invention;

FIG. 45 is a flow chart showing a throttle angle control routine in theninth embodiment;

FIG. 46 is a flow chart showing a processing flow of a target throttleangle calculation routine in the ninth embodiment;

FIG. 47 is a block diagram explaining an engine output increasingcontrol function in the ninth embodiment;

FIG. 48 is a flow chart showing a processing flow of a target throttleangle calculation routine in a tenth embodiment of the presentinvention;

FIG. 49 is a diagram showing conceptually a road surface gradient map inthe tenth embodiment;

FIG. 50 is a flow chart showing a processing flow of a target throttleangle calculation routine in an eleventh embodiment of the presentinvention;

FIGS. 51A and 51B are diagrams each showing conceptually a targetthrottle angle setting map for manual down-shift in the eleventhembodiment;

FIGS. 52A and 52B are diagrams each showing conceptually a targetthrottle angle setting map for auto-down-shift in the eleventhembodiment;

FIGS. 53A and 53B are diagrams each showing conceptually a targetthrottle angle setting map for coast down shift in the eleventhembodiment;

FIG. 54 is a flow chart showing a processing flow of a shift typedetermination routine in the eleventh embodiment;

FIG. 55 is a flow chart showing a processing flow of a shifting oilpressure control routine in the eleventh embodiment;

FIG. 56 is a block diagram explaining an engine output increasingcontrol function in a twelfth embodiment of the present invention; and

FIG. 57 is a flow chart showing a processing flow of a throttle anglecorrection routine in the ninth embodiment.

DETAILED DESCRIPTION OF EMBODIMENT First Embodiment

A first embodiment of the present invention will be described below withreference to FIGS. 1 to 20.

First, a schematic construction of the whole of a control system for anengine 11 as an internal combustion engine will now be described withreference to FIG. 1. An air cleaner 13 is mounted upstream of an intakepipe 12 of the engine 11, and an air flow meter 14 (intake air quantitydetecting means) for measuring an intake air quantity Ga is mounteddownstream of the air cleaner 13. Further, a throttle valve 15 isdisposed downstream of the air flow meter 14. A motor 17 such as a DCmotor is connected to a pivot shaft 15 a of the throttle valve 15. Thedegree of opening (throttle angle) of the throttle valve 15 iscontrolled with a drive force of the motor 17 and is detected by athrottle angle sensor 18.

An injector 20 is attached to an intake manifold 19 which introducesintake air having passed through the throttle valve 15 into eachcylinder in the engine 11, and a spark plug 21 is attached to a cylinderhead of each cylinder in the engine 11. A crank angle sensor 24 isinstalled in opposition to an outer periphery of a signal rotor 23 whichis mounted on a crank shaft 22 of the engine 11. Pulses of an enginespeed signal Ne which is outputted from the crank angle sensor 24 arereceived by an engine ECU (electronic control unit) 25 and an enginespeed is detected from a generated frequency of the engine speed signalNe.

On the other hand, a depressed quantity (acceleration operationquantity) of an accelerator pedal 26 is detected by an acceleratorsensor 27 and a voltage signal Ap proportional to the acceleratoroperation quantity is received by the engine ECU 25 through an A/Dconverter 28. Voltage signals indicative of the intake air quantity Gadetected by the air flow meter 14 and the throttle angle TA detected bythe throttle angle sensor 18 are also received by the engine ECU 25through the A/D converter 28.

The engine ECU 25 is constituted mainly by a microcomputer provided withCPU 29, ROM 30 and RAM 31. Various routines for controlling the enginewhich are stored in the ROM 30 are executed by the CPU 29, whereby anignition timing of the spark plug 21 is controlled and the pulse widthof an injection signal to be applied to the injector 20 is controlled tocontrol the amount of fuel to be injected.

In the engine ECU 25, various routines for controlling the throttlevalve stored in the ROM 30 are executed in the CPU 29, whereby the motor17 for the throttle valve 15 is feedback-controlled, for example by PIDcontrol, through a motor driver 32 in such a manner that the throttleangle detected by the throttle angle sensor 18 becomes coincident with atarget throttle opening. In the event of failure of an electronicthrottle system, a safety circuit disposed in a current path extendingfrom the motor driver 32 to the motor 17 operates to keep the motor 17deenergized. In this state, the throttle angle is held at apredetermined angle so as to permit vehicular running for refuge.

Next, a schematic construction of an automatic transmission 51 will bedescribed with reference to FIGS. 2 and 3. As shown in FIG. 3, an inputshaft 53 of a torque converter 52 is connected to an output shaft of theengine 11 and a hydraulic-driven type speed change gear mechanism 55(shift mechanism) is connected to an output shaft 54 of the torqueconverter 52. In the interior of the torque converter 52, a pumpimpeller 71 and a turbine runner 72, which constitute a fluid coupling,are disposed in opposition to each other, and a stator 73 for uniformingthe flow of oil is disposed between the pump impeller 71 and the turbinerunner 72. The pump impeller 71 is connected to the input shaft 53 ofthe torque converter 52, while the turbine runner 32 is connected to theoutput shaft 54 of the torque converter 52.

Further, in the torque converter 52 there is provided a lock-up clutch56 for engagement or disengagement between the input shaft 53 and theoutput shaft 54 is provided in the torque converter 52. An output torqueof the engine is transmitted to the speed change gear mechanism 55through the torque converter 52 and is shifted by plural gears (e.g.,planetary gears) in the speed change gear mechanism 55, then istransmitted to driving wheels (front or rear wheels) of the vehicle.

In the speed change gear mechanism 55 there are provided plural clutchesC0, C1 and C2 as frictional engaging elements for switching among pluralshift ranges, as well as brakes B0 and B1. As shown in FIG. 4,engagement and release of the clutches C0, C1, C2 and the brakes B0, B1are switched from one to the other hydraulically to change thecombination of power transfer gears, thereby changing the transmissiongear ratio.

FIG. 4 shows engagement combinations of clutches C0, C1, C2 and brakesB0, B1 in a four-shift range automatic transmission, in which circlemarks represent clutches and brakes which are held in an engaged state(torque transfer state) in the shift ranges concerned, while unmarkedportions represent a state of release. For example, in a throttledepressed state in D Range, the transmission shifts up like low, second,third and top gear in this order as the vehicle speed increases. In theshift from low to second gear, B0 is released from the engagement of C0and B0, and B1 is newly engaged. In the shift from second to third gear,B1 is released from the engagement of C0 and B1, and C2 is newlyengaged. In the shift from third to fourth gear, C0 is released from theengagement of C0 and C2, and B1 is newly engaged.

A fail-safe mechanism is provided. According to this mechanism, when B1is fixed in an engaged state without the oil pressure assuming a stateof low pressure by some cause for example at the time of shift fromsecond to third gear, C2 is engaged to prevent the occurrence ofinterlock and stop of the driving wheels. More specifically, oilpressure switches (not shown) are disposed as fail detecting meansclutch by clutch at positions permitting detection of oil pressuresacting on the clutches disposed within the speed change gear mechanism55. The oil switches are each constructed so as to turn ON (Hi output)when an actual oil pressure is not lower than a threshold value and turnOFF (Lo output) when an actual oil pressure is lower than the thresholdvalue. Whether outputs (actual oil pressures) of the oil pressureswitches and oil pressure command values match or not is determined todetect a defective clutch. On the basis of the result of this detectiona control is made so as not to make a shift to a shift range in whichthe aforesaid interlock occurs.

As shown in FIG. 2, a hydraulic pump 58 driven by the engine power isdisposed in the speed change gear mechanism 55, and an oil pressurecontrol circuit 57 is disposed within an oil pan (not shown) whichstores working oil (oil). The oil pressure control circuit 57 includes aline pressure control circuit 59, an automatic shift control circuit 60,a lock-up control circuit 61, and a manual selector valve 66. Workingoil pumped up from the oil pan by the hydraulic pump is fed through theline pressure control circuit 59 to the automatic shift control circuit60 and the lock-up control circuit 61. An oil pressure control valve(not shown) for controlling the oil pressure provided from the hydraulicpump 58 to a predetermined line pressure is provided in the linepressure control circuit 59. Likewise, a plurality of shifting oilpressure control valves (oily pressure control means) for controllingthe oil pressure to be fed to the clutches C0, C1, C2 and brakes B0, B1in the speed change gear mechanism 55 are provided in the automaticshift control circuit 60. Further, a lock-up controlling oil pressurecontrol valve (not shown) for controlling the oil pressure to be fed tothe lock-up clutch 56 is provided in the lock-up control circuit 61.

The oil pressure control valves are each constituted by a linearsolenoid valve for example and control the oil pressure by an attractiveforce which is generated by an electric current flowing under theapplication of voltage at a predetermined duty. Therefore, the electriccurrent in each oil pressure control valve and the oil pressure areclosely related to each other and the oil pressure is controlled bycontrolling the value of the electric current. For absorbing variationsin electric current value against duty, an electric current value ismonitored by current detecting means (not shown) provided in anautomatic transmission electronic control circuit (“AT-ECU” hereinafter)70 and is subjected to a feedback control.

Between the line pressure control circuit 59 and the automatic shiftcontrol circuit 60 there is provided a manual selector valve 66 adaptedto be switched from one to another position in interlock with operationof a shift lever 65. With the shift lever 65 operated to Neutral Range(N Range) or Parking Range (P Range), even in a state in which thesupply of an electric current to the oil pressure control valves in theautomatic shift control circuit 60 is OFF, a switching is made by themanual selector valve 66 so that the oil pressure fed to the speedchange gear mechanism 55 brings the same mechanism into a neutral state.

On the other hand, in the speed change gear mechanism 55 there areprovided an input shaft rotational speed sensor 68 for detecting aninput shaft rotational speed Nt (output shaft rotational speed of thetorque converter 52) of the speed change gear mechanism 55 and an outputshaft rotational speed sensor 69 for detecting an output shaftrotational speed No of the speed change gear mechanism 55.

Output signals provided from these sensors are inputted to the AT-ECU70. The AT-ECU 70 is constituted mainly by a microcomputer. In orderthat the speed change gear mechanism 55 may be shifted in accordancewith preset shift patterns of FIG. 5 by executing various routinesstored in a ROM (storage medium) which is incorporated in themicrocomputer, the supply of an electric current to each of the oilpressure control valves in the automatic shift control circuit 60 iscontrolled in accordance with an operational position of the shift lever65 and operating conditions (e.g., throttle angle and vehicle speed) tocontrol the oil pressure to act on the clutches C0, C1, C2 and thebrakes B0, B1 in the speed change gear mechanism 55, whereby engagementand release of each of the clutches C0, C1, C2 and the brakes B0, B1 areswitched from one to the other to change the combination of powertransfer gears, thereby changing the transmission gear ratio in thespeed change gear mechanism 55.

At this time, for performing a down-shift, the AT-ECU 70 makes a controlas shown in FIGS. 6 and 7. In the following description, the clutchesC01, C1, C2 and the brakes B0, B1 will generically be termed simply“clutches.” Further, in down-shift control, a clutch which switches froman engage state to a released state is designated a “releasing clutch”and a clutch which switches from a released state to an engaged state isdesignated an “engaging clutch.”

FIG. 6 is a time chart showing a control example in “power ONdown-shift” in which the driver depresses the accelerator pedal 26 toeffect a down-shift and FIG. 7 is a time chart showing a control examplein “ETC cooperation down-shift” in which an engine output increasingcontrol is performed during a down-shift not depending on the driver'sintention.

First, a control example in power ON down-shift will be described belowwith reference to FIG. 6.

When the driver depresses the accelerator pedal 26 to a large extent andthe throttle valve is rapidly opened thereby, it is determined that thisstate corresponds to a power ON down-shift, and a down-shift command isissued. At this time point t0 an oil pressure command value for areleasing clutch is decreased to an initial oil pressure and isthereafter decreased at a constant gradient. As a result, the engagingforce of the releasing clutch decreases and the engine load islightened, so that the input shaft rotational speed Nt (output shaftrotational speed of the torque converter 52) in the speed change gearmechanism 55 begins to increase.

Further, at the time pint t0 of output of the down-shift command, an oilpressure command value for an engaging clutch is set to a predeterminedfill oil pressure Po so as to bring about a state just before theengaging clutch produces an engaging force, and a fill control forfilling the engaging clutch with the working oil is performed. At a timepoint t1 corresponding to the state just before development of anengaging force of the engaging clutch after execution of the fillcontrol for only a predetermined time tF, the oil pressure command valuefor the engaging clutch is decreased to a stand-by oil pressure PtAp toterminate the fill control. Thereafter, the state just beforedevelopment of an engaging force of the engaging clutch is maintained bythe stand-by oil pressure PtAp. The stand-by oil pressure PtAp is set ata value close to a set load-equivalent oil pressure PsAp of a returnspring in the engaging clutch.

Thereafter, at a time point t2 at which an increase of the input shaftrotational speed Nt (change rate of Nt >determined value) is detected,the oil pressure of the releasing clutch is subjected to a feedbackcontrol so that an increasing gradient of the input shaft rotationalspeed Nt takes a predetermined value. During this feedback control, theoil pressure command value for the releasing clutch is a little higherthan a set load-equivalent oil pressure PsDr of the return spring. Then,at a time point t3 at which a shift progress ratio SftR [=100×(inputshaft rotational speed Nt−output shaft rotational speed No×gear ratiobefore shift)/(output shaft rotational speed No×gear ratio aftershift−output shaft rotational speed No×gear ratio before shift)] reachesa predetermined value B, a control for increasing the oil pressurecommand value for the engaging clutch at a constant gradient is started.Thereafter, at a time point t4 at which the shift progress ratio SftRreaches a predetermined value A, the oil pressure command value for thereleasing clutch is decreased at a constant gradient.

Further, at a time point t5 at which the shift progress ratio SftRreaches a predetermined value C, the oil pressure command value for theengaging clutch is set to a maximum pressure to increase the oilpressure of the engaging clutch up to the maximum pressure. With thiscontrol, the engaging force of the engaging clutch is increased inconformity with the timing when the input shaft rotational speed Ntincreases to a rotational speed corresponding to a low shift range afterthe down-shift to complete the down-shift.

Next, a control example in ETC cooperation down-shift will be describedwith reference to FIG. 7. At a time point t0 at which an executioncondition for ETC cooperation down-shift exists and a down-shift commandis outputted, an oil pressure command value for a releasing clutch isdecreased rapidly to a stand-by oil pressure PtDr (a little lower oilpressure than the set load-equivalent oil pressure PsDr of the returnspring in the releasing clutch). Thereafter, the state just beforedevelopment of an engaging force of the releasing clutch is maintainedby the stand-by oil pressure PtDr. This is not only for promoting theincrease of the input shaft rotational speed Nt by the engine outputincreasing control but also for suppressing a rush-out feeling of thevehicle caused by the engine output increasing control.

Also in this ETC cooperation down-shift, the oil pressure control forthe engaging clutch is almost the same as in the power ON down-shift. Ata time point t0 at which a down-shift command is outputted, an oilpressure command value for the engaging clutch is set at a predeterminedfill oil pressure Po and a fill control is executed for filling theengaging clutch with working oil. This fill control is executed for apredetermined time tF, and just before the engaging clutch produces anengaging force, the oil pressure command value for the engaging clutchis decreased to a stand-by oil pressure PtAp (near the setload-equivalent oil pressure PsAp of the return spring in the engagingclutch) to terminate the fill control. Thereafter, with the stand-by oilpressure PtAp by the engaging clutch, the engaging force of the engagingclutch is held at a state in which a desired engine brake feeling iscreated. As to the subsequent pressure increasing control, the sameprocessing as in the foregoing power ON down-shift is performed.

This ETC cooperation down-shift is characteristic in that the engineoutput increasing control is performed in the following manner. In thecourse of decrease of the actual oil pressure of the releasing clutchdown to the stand-by oil pressure PtDr and at a time point t6 at whichthe transfer torque capacity of the releasing clutch becomes small orzero and the actual oil pressure decreases to “initial oil pressure” notcausing an acceleration feeling even with an increase of the engineoutput, the engine output increasing control is started.

In this case, for estimating the time point t6 at which the actual oilpressure of the releasing clutch decreases to a level of not higher thanthe initial oil pressure, a response of the actual oil pressure to theoil pressure command value for the releasing clutch is approximatedusing the transfer characteristic of “first order lag +time delay,” thenan estimated value of the actual oil pressure calculated using the saidtransfer characteristic is compared with the initial oil pressure, andat the time point t6 at which the estimated value of the actual oilpressure decreases to the initial oil pressure, it is determined thatthe start timing of the engine output increasing control has beenreached.

At this time point t6, that is, when it is determined that the starttiming of the engine output increasing control has been reached, thethrottle angle command value is set to a predetermined throttle openingcommand value and a throttle opening control is started. Then, at asomewhat delayed time point t7, Fuel Cut Flag (“F/C Flag” hereinafter)is turned OFF and a fuel injection return control is started to resumethe injection of fuel.

With a predetermined time lag after the start of the engine outputincreasing control (the throttle opening control and the fuel injectionreturn control), the engine output increases. As causes of the delay ofthe engine output increasing control there are, in the throttle openingcontrol, a response delay (Ta) of an opening motion of the throttlevalve 15 and a response delay (Tb) in the period after actual opening ofthe throttle valve 15 until increase of the engine output. In the fuelinjection return control, there is a response delay (Tc) in the periodafter resuming of fuel injection until increase of the engine output.

As to the response delay (Ta) of an opening motion of the throttle valve15, it is calculated using a map of parameters (e.g., cooling watertemperature and battery voltage) associated with the drive responsivityof the motor 17 in the electronic throttle system. As to the responsedelay (Tb) in the period after opening of the throttle valve 15 untilincrease of the engine output, it is calculated using a delay in theperiod after the introduction of intake air in an increased amount byopening of the throttle valve 15 into a cylinder until combustion and amap of parameters (e.g., engine speed and throttle angle) associatedwith the intake air flow velocity. As to the delay (Tc) in the periodafter resuming of the fuel injection until increase of the engineoutput, it is set by the time (time T720°CA required for the crank shaftto rotate 720°CA) after the injection of fuel until, combustion.

Once the start of control is determined by the start timingdetermination in the foregoing throttle opening control (engine outputincreasing control), a throttle opening command value set so as to givean input shaft rotational speed Nt behavior which realizes desired shifttime and shift feeling is outputted and held. This throttle openingcommand value is set on the basis of detection results of friction lossof the engine 11 and parameters [e.g., shift pattern (gear ratiochange), cooling water temperature, and input shaft rotational speed Nt]which exert an influence on the amount of change in the input shaftrotational speed Nt before and after a shift, as well as a desired shifttime. Further, if the throttle opening command value is changed inaccordance with the magnitude of a road surface gradient and that ofdeceleration of the vehicle body, it is possible to let the feelingmatch a desired state more minutely. In this case, the throttle openingvalue is set small in deceleration and large in acceleration. Thethrottle opening value is corrected in accordance with output of the airflow meter 14. As a result, the input shaft rotational speed Nt (of thespeed change gear mechanism 55 (output shaft rotational speed of thetorque converter 52) begins to increase upon arrival of the oil pressureof the releasing clutch at the stand-by oil pressure PtDr orthereabouts.

During execution of this engine output increasing control, apredetermined engine output increase quantity is maintained while makingan end determination for terminating the actual engine output increaseby the engine output increasing control in conformity with the timepoint at which the down-shift ends finally (a time point at which theshift progress ratio SftR becomes 100%). This end determination is madetaking into account a response delay in the period after the issuance ofan end command until an actual termination of the engine output increaseon the basis of the shift progress ratio SftR and a change quantityΔSftR per unit time ΔT of the shift progress ratio. As to a control endtiming cable of offsetting this response delay, a time pointcorresponding to the value of the shift progress ratio SftR iscalculated and whether a predetermined state corresponding to asubstantial termination of the down-shift has been reached or not isdetermined on the basis of whether the shift progress ration SftR hasexceeded or not the calculated value of the above time point, then endtimings (t8, t9) of the throttle opening control as the engine outputincreasing control and the fuel injection return control are determined.As a result, if the end timings (t8, t9) are determined, then in thethrottle opening control, an end control is performed for decreasing thethrottle opening command value to “0.” In this end control, the throttleopening command value is decreased to “0” with a predetermined gradientfor ensuring a transient reproducibility in electronic throttle. As tothe fuel injection return control, F/C Flag is returned to ON inaccordance with the end determination to resume fuel cut. However, thisdoes not apply when the request for fuel cut from the engine 11 vanishesdue to a sudden decrease of the engine speed or by any other cause.

As causes of the engine output increase end response delay there are, inconnection with the throttle opening control, a response delay (Td) of afull closing motion of the throttle valve 15, a response delay (Te) inthe period after actual full closing of the throttle valve 15 untilactual disappearance of the engine output increase, and time (Tsd) afterthe end determination until decrease of the throttle opening commandvalue to “0.” As to the fuel injection return control, there is aresponse delay (Tf) in the period after resuming of fuel cut untildisappearance of the engine output.

As to the response delay (Td) of a closing motion of the throttle valve15, it is calculated using a map of parameters (e.g., cooling watertemperature and battery voltage) associated with the drive responsivityof the motor 17 in the electronic throttle system. As to the responsedelay (Te) in the period after full closing of the throttle valve 15until disappearance of the engine output increase, it is calculatedusing a delay in the period after introduction of intake air in anamount decreased by full closing of the throttle value 15 into acylinder until combustion and a map of parameters (e.g., engine speedand throttle angle) associated with the intake air flow velocity. As tothe time (Tsd) after the end determination until decrease of thethrottle opening command value to “0,” it is calculated on the basis ofthrottle opening command value/decrease gradient. As to the responsedelay (Tf) in the period after resuming of fuel cut until disappearanceof the engine output, it is set by the time (time T720° CA required forthe crank shaft to rotate 720° CA) after resuming of fuel cut untilarrival of the fuel-cut cylinder at a combustion stroke.

On the other hand, as to the oil pressure command value for thereleasing clutch, it is decreased at a constant gradient upon arrival ofthe shift progress ration SftR at 100%. The ETC cooperation down-shiftis completed by this control.

The shift control in this first embodiment described above is performedby cooperation of both AT-ECU 70 and engine ECU 25 and in accordancewith various routines, whose contents will be described below.

Shift Control

A shift control routine shown in FIG. 8 is a main routine of shiftcontrol which is executed at every predetermined time (e.g., every 8 to32 msec) during engine operation. Once this routine is started, first inStep 100 it is determined whether a shift is necessary or not (whether ashift command has been outputted or not), and if a shift is notnecessary, this routine is ended without performing any subsequentprocessing.

On the other hand, if a shift is necessary, the processing flow advancesto Step 101, in which a shift type determination routine of FIG. 9 to bedescribed later is executed to determine a shift type corresponding tothe present shift command. Thereafter, the processing flow advances toStep 102, in which it is determined whether ETC Cooperation Down-ShiftExecution Flag xEtc is set ON meaning that there exist ETC cooperationdown-shift execution conditions. If the Flag xEtc is set OFF, theprocessing flow advances to Step 105, in which a shifting oil pressurecontrol routine (not shown) according to the shift type is executed tomake shift to the shift range conforming to the present shift commandand this routine is ended.

On the other hand, if ETC Cooperation Down-Shift Execution Flag xEtc isset ON, the processing flow advances from Step 102 to Step 103,in whicha throttle opening control routine of FIG. 13 to be described later isstarted and a throttle opening control is executed, then in Step 104which follows, a fuel injection return control routine of FIG. 18 to bedescribed later is started and a fuel injection return control isexecuted. Thereafter, the processing flow advances to Step 105, in whicha shifting oil pressure control routine of FIG. 10 is executed to makeshift to the shift range conforming to the present shift command andthis routine is ended.

Shift Type Determination

The following description is now provided about processing contents of ashift type determination routine of FIG. 9 which is executed in Step 101in the shift control routine of FIG. 8. Once the shift typedetermination routine is started, first in Step 111 it is determinedwhether the present shift command concerns an up-shift or a down-shift,and if it is determined that the present shift command concerns anup-shift, the processing flow advances to Step 112, in which it isdetermined whether the load condition imposed on the automatictransmission 51 is power ON (the automatic transmission 51 is drivenfrom the engine 11 side) or power OFF (the automatic transmission 51 isdriven from the driving wheels side). Then, in accordance with theresult of this determination it is determined whether the shift typeconforming to the present shift command corresponds to which of a powerON up-shift (Step 118) and a power OFF up-shift (Step 119).

On the other hand, if it is determined in Step 111 that the presentshift command concerns a down-shift, the processing flow advances toStep 113, in which it is determined whether the load condition imposedon the automatic transmission 51 is power ON or power OFF, and if it isdetermined to be power OFF, a check is made to see if the shift type isa down-shift based on the driver's intention of deceleration. In thecase of either a select shift by operation of the shift lever 16 or asports shift by operation of a switch mounted on the steering portion orby operation of the shift lever 16 in manual mode, it is determined thatthe present shift command concerns a down-shift based on the driver'sintention of deceleration. Then, the processing advances to Step 116, inwhich it is determined whether an execution condition for ETCcooperation down-shift exists or not. For example, for ensuringcontrollability, it is determined whether the working oil temperaturelies in a temperature range superior in response reproducibility to theoil pressure command value. If it is determined that the ETC cooperationdown-shift execution condition exists, the processing flow advances toStep 117, in which ETC Cooperation Down-Shift Execution Flag xEtc is setON. Thereafter, the processing flow advances to Step 121, in which it isdetermined that the present shift type is the ETC cooperationdown-shift.

When it is determined in Step 115 that the present shift commandconcerns a down-shift based on the driver's intention of deceleration,or when it is determined in Step 116 that the ETC cooperation down-shiftexecution condition does not exist, the processing flow advances to Step122, in which it is determined that the present shift type is a powerOFF down-shift.

On the other hand, if power ON is determined in Step 113, the processingflow advances to Step 114 for distinguishing between power ON based onthe ETC cooperation down-shift control (engine output increasingcontrol) and power ON based on depression of the accelerator pedal 26.In Step 114 it is determined whether ETC Cooperation Down-ShiftExecution Flag xEtc is set ON or not, and if it is set ON, theprocessing flow advances to Step 121, in which it is determined that thepresent shift type is the ETC cooperation down-shift. Then, if ETCCooperation Down-Shift Execution Flag xEtc is set OFF, the processingflow advances to Step 120, in which it is determined that the presentshift type is a power ON down-shift.

Shifting Oil Pressure Control

A shifting oil pressure control routine of FIG. 10 is executed when theshift type is the ETC cooperation down-shift. Once this routine isstarted, first in Step 131 there is executed a releasing clutch oilpressure control routine of FIG. 11 which will be described later tocontrol the oil pressure of a releasing clutch. Then, in Step 132 whichfollows, an engaging clutch oil pressure control routine of FIG. 12 tobe described later is executed to control the oil pressure of anengaging clutch.

Thereafter, the processing flow advances to Step 133, in which whetherthe down-shift has been completed or not is determined on the basis ofwhether Control Stage Flags 1 and 2 to be described later are equal to 4and 5, respectively. Upon completion of the down-shift, the processingflow advances to Step 134, in which both Control Stage Flags 1 and 2 arereset to an initial value “0” and all the other Flags xEtc, xEtcTSt,xEtcFSt, xEtcTEd and xEtcFEd are reset to “OFF” to terminate thisroutine.

Releasing Clutch Oil Pressure Control

Next, the following description is provided about processing contents ofa releasing clutch oil pressure control routine of FIG. 11 which isexecuted in Step 131 in the shifting oil pressure control routine ofFIG. 10. Once this routine is started, first in Step 141 it isdetermined in what stage the present releasing clutch oil pressurecontrol lies. This determination is made on the basis of to which of 0to 3 the value Control Stage Flag 1 corresponds. Control Stage Flag 1 isa flag which increments one at every progress to each stage in thereleasing clutch oil control, with an initial value being 0 and amaximum value 4. Therefore, the releasing clutch oil pressure control isa four-stage sequence control.

At a time point t0 at which the releasing clutch oil pressure control isstarted, Control Stage Flag 1 is set to the initial value (0) andtherefore the processing flow advances to Step 142, in which ControlStage Flag 1 is set to “1.” Then, the processing flow advances to Step143, in which an initial value of an estimated real oil pressure valuePreal of a releasing clutch (y) which is controlled for release in theETC cooperation down-shift of this time is updated by an oil pressurecommand value PyDr for the releasing clutch (y). Thereafter, theprocessing flow advances to Step 144, in which an oil pressure commandvalue for the releasing clutch is set to the stand-by oil pressure PtDrand the oil pressure to be fed to the releasing clutch is therebylowered to the stand-by oil pressure PtDr (first-stage control).

At the time of the next starting of this routine the Flag 1 is alreadyequal to 1 and therefore the processing flow advances to Step 145, inwhich the oil pressure of the releasing clutch is held at the stand-byoil pressure PtDr. Then, in the next Step 146 it is determined whetherthe shift progress ratio SftR has reached a predetermined value F closeto 100%, and if the answer is affirmative, this routine is ended.Thereafter, upon arrival of the shift progress ratio SftR at thepredetermined value F the processing flow advances to Step 147, in whichControl Stage Flag 1 is set to “2” and this second-stage control isended, followed by shift to the third-stage control.

In the third-stage control, first in Step 148 the oil pressure commandvalue for the releasing clutch is decreased at a constant gradient.Then, in the next Step 149, it is determined whether the oil pressurecommand value for the releasing clutch has decreased to a value of notlarger than 0. This third-stage control (oil pressure decreasingcontrol) is continued until the oil pressure command value for thereleasing clutch decreases to a value of not larger than 0. Thereafter,when the oil pressure command value for the releasing clutch decreasesto a minimum value (0 or smaller), the processing flow advances to Step150, in which Control Stage Flag 1 is set to “3” and the third-stagecontrol is ended, followed by shift to the fourth-stage control.

In the fourth-stage control, first in Step 151 the oil pressure commandvalue for the releasing clutch is set to 0 to maintain the releasingclutch in a completely released state. Then, in the next step 152,Control Stage Flag 1 is set to “4” and the releasing clutch oil pressurecontrol is ended.

Engaging Clutch Oil Pressure Control

Next, the following description is provided about processing contents ofan engaging clutch oil pressure control routine of FIG. 12 which isexecuted in Step 132 in the shifting oil pressure control routine ofFIG. 10. Once this routine is started, first in Step 161 it isdetermined in what stage the present engaging clutch oil pressurecontrol lies. This determination is performed on the basis of to whichof 0 to 4 the value of Control Stage Flag 2 corresponds. Control StageFlag 2 is a flag which increments one at every progress to each stage inthe engaging clutch oil pressure control, with an initial value being 0and a maximum value 5. Thus, the engaging clutch oil pressure control isa five-stage sequence control.

At a time point t0 at which the engaging clutch oil pressure control isstarted, Control Stage Flag 2 is set to the initial value (0) andtherefore the processing flow advances to Step 162, in which an oilpressure command value for the engaging clutch is set to a predeterminedfill oil pressure Po and a fill control for filling the engaging clutchwith working oil is executed. Then, in Step 163 which follows, ControlStage Flag 2 is set to “1” and thereafter the processing flow advancesto Step 164, in which a timer (t) for counting the fill control time isreset to 0 to terminate this routine.

When this routine is started next time, Flag 2 is already set equal to 1and therefore the processing flow advances to Step 165, in which thefill control time timer (t) is counted up to count the fill control timeso far elapsed. Then, in Step 166 which follows, it is determinedwhether the value of the timer (t) has reached a predetermined time tFor longer. Until the fill control time reaches the predetermined timetF, the oil pressure command value for the engaging clutch is held atthe fill oil pressure Po and the fill control is continued (Step 169).

The predetermined time tF is a time necessary for producing by the fillcontrol a state just before the engaging clutch develops an engagingforce and it is set beforehand by experiment or simulation.

Thereafter, when the fill control time reaches the predetermined time tF(when the state just before development of an engaging force by theengaging clutch is reached by the fill control), the processing flowadvances to Step 167, in which Control Stage Flag 2 is set to “2.” Then,in the next Step 168, the oil pressure command value for the engagingclutch is decreased to a stand-by oil pressure PtAp to terminate thefill control. Thereafter, the state just before development of anengaging force by the engaging clutch is held by the stand-by oilpressure PtAp.

When the oil pressure of the engaging clutch is controlled to thestand-by oil pressure PtAp, Control Stage Flag 2 is “2” and thereforethe processing flow advances to Step 170, in which it is determinedwhether the shift progress ratio SftR has reached a predetermined valueD (see FIG. 7) or larger. Until the shift progress ratio SftR reachesthe predetermined value D or larger, the oil pressure command value forthe engaging clutch is held at the stand-by oil pressure PtAp (Step173).

Thereafter, upon arrival of the shift progress ratio SftR at thepredetermined value D or larger, the processing flow advances to Step171, in which Control Stage Flag 2 is set to “3.” Then, in the next Step172, a shift is made to a control in which the oil pressure commandvalue for the engaging clutch is increased at a constant gradient.

Subsequently, when this routine is started, Control Stage Flag 2 is “3”and therefore the processing flow advances to Step 174, in which it isdetermined whether the shift progress ratio SftR has reached apredetermined value G close to 100%. Until the shift progress ratio SftRreaches the predetermined value G, the control for increasing the oilcommand value for the engaging clutch at a constant gradient iscontinued (Step 177).

Thereafter, upon arrival of the shift progress ratio SftR at thepredetermined value G, the processing flow advances to Step 175, inwhich Control Stage Flag 2 is set to “4.” Then, in the next Step 176,the oil pressure command value for the engaging clutch is set to amaximum pressure to increase the oil pressure of the engaging clutch upto the maximum pressure. With this control, the engaging force of theengaging clutch is increased in conformity with the timing of increaseof the input shaft rotational speed Nt to a rotational speed equivalentto a lower shift range as a to-be-down-shifted range, and the down-shiftis completed.

Subsequently, when this routine is started, since Control Stage Flag 2is “4,” the processing flow advances to Step 178, in which it isdetermined whether a predetermined time has elapsed after the setting ofControl Stage Flag 2 to “4” (that is, whether the predetermined time aselapsed or not after arrival of the shift progress ratio at thepredetermined value G). If the answer is affirmative, the processingflow advances to Step 179, in which Control Stage Flag 2 is set to “5”and the engaging clutch oil pressure control is ended.

Throttle Opening Control

A throttle opening control routine shown in FIG. 13 is a subroutinewhich is executed in the shift control routine of FIG. 8 and it plays arole as engine output increasing control recited in the appended claims.

When this routine is started, first in Step 201, it is determinedwhether Throttle Opening Control Start Flag xEtcTSt is OFF which means astate before start of the throttle opening control. If the Flag is OFF,the processing flow advances to Step 203, in which a throttle openingcontrol start determination routine of FIG. 14 to be described later isexecuted and it is determined whether a throttle opening control starttiming has been reached or not. Then, in accordance with the result ofthe determination Throttle Opening Control Start Flag xEtcTSt is set orreset.

Thereafter, the processing flow advances to Step 205, in which it isdetermined whether Throttle Opening Control Start Flag xEtcTSt remainsOFF or not. If the Flag is OFF, the processing flow advances to Step207, in which a stored value of intake air quantity before start of thethrottle opening control is updated by the present value GaB detected bythe air flow meter 14 and this routine is ended.

On the other hand, when it is determined in Step 205 that ThrottleOpening Control Start Flag xEtcTSt is set ON, the processing flowadvances to Step 209, in which a throttle angle command value tangleat(throttle opening quantity) is set using a throttle opening setting mapof FIG. 17 and in accordance with a down-shift range, water temperatureand input shaft rotational speed Nt. Thereafter, the processing flowadvances to Step 210, in which a throttle opening quantity correctioncontrol routine of FIG. 16 to be described later is executed and thisroutine is ended.

If it is determined in Step 201 that Throttle Opening Control Start FlagxEtcTSt is ON which means that the throttle opening control is beingexecuted, the processing flow advances to Step 202, in which it isdetermined whether Throttle Opening Control End Flag xEtcTEd is OFFwhich means a state before end of the throttle opening control. If theFlag is OFF, the processing flow advances to Step 204, in which athrottle opening control end determination routine of FIG. 15 to bedescribed later is executed and a check is made to see if a throttleopening control end timing has reached or not. Then, Throttle OpeningControl End Flag xEtcTEd is set or reset in accordance with the resultof the determination.

Subsequently, the processing flow advances to Step 206, in which it isdetermined whether Throttle Opening Control End Flag xEtcTEd remains OFFor not. If the Flag is OFF, the processings of Steps 209 and 210 areexecuted and the throttle opening control is continued.

On the other hand, if it is determined in Step 206 that Throttle OpeningControl End Flag xEtcTEd is set ON, the processing flow advances to Step208, in which an end control involving decreasing the throttle openingcommand value tangleat in decrement of a predetermined quantitydtangleat to “0” at a predetermined gradient is executed.

Throttle Opening Control Start Determination

A throttle opening control start determination routine of FIG. 14 is asubroutine which is executed in Step 203 in the throttle opening controlroutine of FIG. 13 and it plays a role as output increase start timingcontrol means recited in the appended claims.

When this routine is started, first in Step 221, an estimated real oilpressure value Preal of a releasing clutch (y) which is controlled forrelease in the ETC cooperation down-shift of this time is approximatedusing a first order lag system of an oil pressure command value PyDr forthe releasing clutch (y) and is calculated by the following weightedaveraging operation equation:Preal=m·PyDr+(1−m)·PrealO

In the above equation, PrealO stands for an estimated real oil pressurevalue of the last time and m stands for weighted averaging coefficient(0<m<1). An initial value of the estimated real oil pressure value Prealis set to the oil pressure command value PyDr for the releasing clutchjust before stand-by oil pressure setting in Step 143 in the releasingclutch oil pressure control routine of FIG. 11.

In the above equation the weighted averaging coefficient m may be afixed value which is preset for simplification of the arithmeticprocessing, but taking into account the point that the responsivity ofthe real oil pressure to the oil pressure command value PyDr variesdepending on oil temperature (viscosity of working oil) and the type ofclutch, the weighted averaging coefficient m may be calculated using amap or a mathematical expression in accordance with oil temperature orthe type of clutch.

After calculation of the estimated real oil pressure value Preal, theprocessing flow advances to Step 222, in which the estimated real oilpressure value Preal calculated this time is stored as an initial valueof an estimated real oil pressure value PrealF in a response delayperiod which will be described later. Then, the processing flow advancesto Step 223, in which a counter (count) for counting the number of timesof calculation of the estimated real oil pressure value PrealF in theresponse delay period is reset to 0. Subsequently, the processing flowadvances to Step 224, in which a response delay (Ta) of an openingmotion of the throttle valve 15 and a response delay (Tb) in the periodafter actual opening of the throttle valve 15 until an increase of theengine output are calculated. In this case, as to the response delay(Ta) of an opening motion of the throttle valve 15, it is calculatedusing a map of parameters (e.g., cooling water temperature and batteryvoltage) associated with the drive responsivity of the motor 17 in theelectronic throttle system. As to the response delay (Tb) in the periodafter opening of the throttle valve until an increase of the engineoutput, it is calculated using a delay in the period after introductionof intake air in an amount increased by opening of the throttle valve 15into a cylinder until combustion and a map of parameters (e.g., enginespeed and throttle angle) associated with the intake air flow velocity.

Thereafter, the number of times N of calculation of the estimated realoil pressure value PrealF in the total time (Ta+Tb) of the above tworesponse delays is calculated.N=(Ta+Tb)/tcal

In the above equation, tcal stands for a calculation cycle of theestimated real oil pressure value Preal. The number of times N ofcalculation is calculated to an integer value by omission or rounding ofdecimals.

Thereafter, the processing flow advances to Step 226, in which it isdetermined whether the value of the counter (count) has reached the N ornot. If the answer is negative, the processing flow advances to Step227, in which the estimated real oil pressure value PrealF in theresponse delay period is approximated by a first order lag system of theoil pressure command value PyDr and is calculated by the followingweighted averaging operation equation:PrealF=m·PyDr+(1−m)·PrealFO

In the above equation, PrealFO stands for an estimated real oil pressurevalue PrealF of the last time and m stands for the weighted averagingcoefficient (0<m<1). Thereafter, in Step 228, the counter (count) iscounted up for return to Step 226. By repeating such processings, thecalculation of the estimated real oil pressure value PrealF in theresponse delay period is repeated until the value of the counter (count)reaches the foregoing N.

Upon arrival of the counter (count) value at the foregoing N, theprocessing flow advances from Step 226 to Step 229, in which it isdetermined whether the estimated real oil pressure value PrealF hasdecreased to an initial oil pressure (a predetermined transfer torquecapacity-equivalent oil pressure) or lower. The initial oil pressure (apredetermined transfer torque capacity-equivalent oil pressure) is setto such an oil pressure as does not cause an acceleration feeling evenwhen the transfer torque capacity of the releasing clutch becomes smallor zero and the engine output increases. The initial oil pressure may bea preset fixed value for simplification of the arithmetic processing,but taking into account the point that the oil pressure not causing anacceleration feeling even with an increase of the engine output variesdepending on the type of clutch and input torque Tin, the initial oilpressure may be calculated using a map or a mathematical expression inaccordance the type of clutch of input torque Tin.

The input torque Tin may be estimated for example by the followingequation on the basis of engine operating conditions and characteristicsof the torque converter 52:Tin=C(e)×tr(e)×Ne ²C (e): torque converter capacity coefficient

-   -   Tr (e): torque ratio    -   Ne: engine speed

The torque converter capacity coefficient C (e) and the torque ratio tr(e) are each calculated using a map or a mathematical expression inaccordance with a speed ratio (e) (=Nt/Ne).

There also may be adopted a method wherein an output torque of theengine 11 is calculated on the basis of an intake air quantity or athrottle angle and is then multiplied by the above torque ratio tr (e)to obtain an input shaft torque Tin.

When it is determined in Step 229 that the estimated real oil pressurevalue PrealF has not been decreased to the initial oil pressure or less,this routine is ended. Then, upon decrease of the estimated real oilpressure value PrealF to the initial oil pressure or less, theprocessing flow advances to Step 230, in which there is performed adelay processing for a time delay Tm in oil pressure response.Thereafter, the processing flow advances to Step 231, in which ThrottleOpening Control Start Flag xEtcTst is set ON and this routine is ended.

Throttle Opening Control End Determination

A throttle opening control end determination routine of FIG. 15 is asubroutine which is executed in Step 204 in the throttle opening controlroutine of FIG. 13, playing a role as output increase end timing controlmeans recited in the appended claims. Once this routine is started,first in Step 241 there are calculated a response delay (Td) of a fullclosing motion of the throttle valve 15, a response delay (Te) in theperiod after actual full closing of the throttle valve 15 until actualdisappearance of the engine output increase, and time (Tsd) requiredafter end determination until decrease of a throttle opening commandvalue to “0.” As to the response delay (Td) of a closing motion of thethrottle valve 15, it is calculated using a map of parameters (e.g.,cooling water temperature and battery voltage) associated with the driveresponsivity of the motor 17 in the electronic throttle system. As tothe response delay (Te) in the period after full closing of the throttlevalve 15 until disappearance of the engine output increase, it iscalculated using a delay in the period after introduction of intake airin an amount decreased by full closing of the throttle valve 15 untilcombustion and a map of parameters (e.g, engine speed and throttleangle) associated with the intake air flow velocity. Further, as to thetime (Tsd) in the period after end determination until decrease of athrottle opening command value to “0,” it is calculated on the basis ofa throttle opening command value decreasing gradient. The process ofStep 241 plays a role as response delay calculating means recited in theappended claims.

Thereafter, the processing flow advances to Step 242, in which a shiftprogress ratio SftRed at the end of the throttle opening control (at thestart of end control) is calculated by the following equation:SftRed=100−DSftRx(Td+Te+Tsd)/tsmp

In the above equation, DSftR stands for a change quantity (this timevalue−last time value) per calculation cycle of the shift progress ratioSftR and tsmp stands for a calculation cycle of DSftR. The shiftprogress ratio SftRed at the end of the throttle opening control (at thestart of end control) is set in accordance with the above equation andtaking into account a system response delay (Td+Te+Tsd) associated withthe end of the throttle opening control relative to an after-shift gearratio (SftR=100%).

Thereafter, the processing flow advances to Step 243, in which it isdetermined whether the present shift progress ratio SftR has reached theabove SftRed or more. If the answer is negative, this routine is ended.Then, upon arrival of the shift progress ratio SftR at the above SftRed,it is determined that a predetermined state corresponding to asubstantial end of the down-shift has been reached, and the processingflow advances to Step 244, in which Throttle Opening Control End FlagxEtcTEd is set ON.

Throttle Opening Quantity Correction Control

A throttle opening quantity correction control routine of FIG. 16 is asubroutine which is executed in Step 210 in the throttle opening controlroutine of FIG. 13. Once this routine is started, first in Step 251 itis determined whether an execution condition for a throttle openingquantity correction control exists or not. For example, thisdetermination is made on the basis of whether an elapsed time after theissuance of a throttle opening command is a response delay-equivalenttime or longer. If the said elapsed time is shorter than the responsedelay-equivalent time, the execution condition for the throttle openingquantity correction control is not established and this routine isended. Upon subsequent arrival of the said elapsed time at the responsedelay-equivalent time or longer, the execution condition for thethrottle opening quantity correction control is established and theprocessing flow advances to Step 252, in which the throttle anglecommand value tangleat (throttle opening quantity) is corrected by thefollowing equation:tangleat=tangleat×DGaT/(Ga−GaB)

In the above equation, DGaT stands for a target increment value of theintake air quantity Ga by the throttle opening control and it is setusing a table or the like in accordance with the throttle angle commandvalue tangleat, and GaB stands for an intake air quantity just beforestart of the throttle opening control which has been stored in Step 207in the throttle opening control routine of FIG. 13. By correcting thethrottle angle command value tangleat (throttle opening quantity inaccordance with the above equation there are corrected variation insystem manufacture, variations caused by secular change, and variationsbased on operating conditions such as atmospheric pressure and intakeair temperature.

Fuel Injection Return Control

A fuel injection return control routine of FIG. 18 is a subroutineexecuted in Step 104 in the shift control routine of FIG. 8, playing arole as engine output increasing control means recited in the appendedclaims. Once this routine is started, first in Step 300 it is determinedwhether there is a request for fuel cut on the engine side, and if theanswer is negative, the processing flow advances to Step 307, in whichthe fuel injection is continued.

On the other hand, if it is determined in Step 300 that there is arequest for fuel cut (fuel is being cut), the processing flow advancesto Step 301, in which it is determined whether Fuel Injection ReturnControl Start Flag xEtcFSt is OFF which means a state before start ofthe fuel injection return control. If the Flag is OFF, the processingflow advances to Step 303, in which a fuel injection start determinationroutine of FIG. 19 to be described later is executed and a check is madeto see if a start timing of the fuel injection return control has beenreached or not. Then, Fuel Injection Return Control Start Flag xEtcFStis set or reset in accordance with the result of the determination.

Subsequently, the processing flow advances to Step 305, in which it isdetermined whether Fuel Injection Return Control Start Flag xEtcFStremains OFF or not. If the Flag remains OFF, this routine is ended,while if it is determined that the Flag is set ON, the processing flowadvances to Step 308, in which fuel injection is performed.

If it is determined in Step 301 that Fuel Injection Return Control StartFlag xEtcFSt is ON which means a state of the fuel injection returncontrol being under execution, the processing flow advances to Step 302,in which it is determined whether Fuel Injection Return Control End FlagxEtcFEd is OFF meaning a state before end of the fuel injection returncontrol. If the Flag is OFF, the processing flow advances to Step 304,in which a fuel injection return control end determination routine ofFIG. 20 to be described later is executed and a check is made to see ifan end timing of the fuel injection return control has been reached ornot. Then, Fuel Injection Return Control End Flag xEtcFEd is set orreset in accordance with the result of the determination.

Thereafter, the processing flow advances to Step 306, in which it isdetermined whether Fuel Injection Return Control End Flag xEtcFEdremains OFF or not. If the Flag remains OFF, the processing flowadvances to Step 308, in which fuel injection is performed.

If it is determined in Step 306 that Fuel Injection Return Control EndFlag xEtcFEd is ON meaning the end of the fuel injection return control,the processing flow advances to Step 309, in which fuel cut is resumed.

Fuel Injection Start Determination

A fuel injection start determination routine of FIG. 19 is a subroutinewhich is executed in Step 303 in the fuel injection return controlroutine of FIG. 18, playing a role as output increase start timingcontrol means recited in the appended claims.

Once this routine is started, first in Step 321, an estimated real oilpressure value Preal of a releasing clutch of this time is calculated bythe following weighted averaging operation equation in the same way asin Step 221 in FIG. 14 and using an oil pressure command value PyDr forthe releasing clutch, an estimated real oil pressure value PrealO ofthis time and the weighted averaging coefficient m:Preal=m·PyDr+(1−m)·PrealO

Thereafter, the processing flow advances to Step 322, in which theestimated real oil pressure value Preal calculated this time is storedas an initial value of an estimated real oil pressure value PrealF in aresponse delay period to be described later. Then, the processing flowadvances to Step 323, in which the counter (count) for counting thenumber of times of calculation of the real oil pressure estimated valuePrealF in the response delay period is reset to 0. Subsequently, theprocessing flow advances to Step 324, in which a response delay (Tc) inthe period after resuming of fuel injection until an increase of engineoutput is calculated. In this case, time T720° CA required for thecrankshaft to rotate 720° CA is calculated as the response delay (Tc).

Thereafter, the processing flow advances to Step 325, in which thenumber of times M of calculation of the estimated real oil pressurevalue PrealF in the response delay (Tc) is calculated.M=Tc/tcal

In the above equation, tcal stands for a calculation period of theestimated real oil pressure value Preal. The number of times M ofcalculation is calculated to an integer value by omission or rounding ofdecimals.

Subsequently, the processing flow advances to Step 326, in which it isdetermined whether the value of the counter (count) has reached theabove M or not. If the answer is negative, the processing flow advancesto Step 327, in which the estimated real oil pressure value PrealF inthe response delay period is calculated by the weighted averagingoperation of the oil pressure command value PyDr.PrealF=m·PyDr+(1−m)·PrealFO

Thereafter, in Step 328, the counter (count) is counted up and theprocessing flow returns to Step 326. By repeating such processings, thecalculation of the estimated real oil pressure value PrealF in theresponse delay period is repeated until the value of the counter (count)reaches the above M.

Upon arrival of the counter (count) value at the above M, the processingflow advances from Step 326 to Step 329, in which, as in Step 229 shownin FIG. 14, it is determined whether the estimated real oil pressurevalue PrealF has decreased to an initial oil pressure (a predeterminedtransfer torque capacity-equivalent oil pressure) or lower. The initialoil pressure (a predetermined transfer torque-equivalent oil pressure)is set to such an oil pressure as does not create an accelerationfeeling even when the transfer torque capacity on the releasing clutchbecomes small or zero and the engine output increases. When it isdetermined in Step 329 that the estimated real oil pressure value PrealFhas not yet decreased to the initial oil pressure or lower, this routineis ended. Then, when the estimated real oil pressure value has decreasedto the initial oil pressure or lower, the processing flow advances toStep 330, in which there is performed a delay processing for a timedelay Tm in oil pressure response. Then, the processing flow advances toStep 331, in which Fuel Injection Return Control Start Flag xEtcFSt isset ON and this routine is ended.

Fuel Injection End Determination

A fuel injection end determination routine of FIG. 20 is a subroutinewhich is executed in Step 304 in the fuel injection return controlroutine of FIG. 18, playing a role as output increase end timing controlmeans recited in the appended claims. Once this routine is started,first in Step 341, a response delay (Tf) in the period after resuming offuel cut until disappearance of engine output is calculated. In thiscase, time T720° CA required for the crankshaft to rotate 720° CA iscalculated as the response delay (Tf).

Thereafter, the processing flow advances to Step 342, in which a shiftprogress ratio SftRed at the end of the fuel injection return control(at the start of end control) is calculated by the following equation:SftRed=100−DSftR×Tf/tsmp

In the above equation, DSftR stands for a change quantity (this timevalue−last time value of SftR) per calculation cycle of the shiftprogress ratio SftR and tsmp stands for a calculation cycle of DSftR. Inaccordance with the above equation the shift progress ratio SftRed atthe end of the fuel injection return control (at the start of endcontrol) is set taking into account the response delay (Tf) of thesystem associated with the end of the fuel injection return controlrelative to an after-shift gear ratio (SftR=100%).

Thereafter, the processing flow advances to Step 343, in which it isdetermined whether the present shift progress ratio SftR has reached theSftRed or higher, and if the answer is negative, this routine is ended.Upon arrival of the shift progress ratio SftR at the above SftRed, theprocessing flow advances to Step 344, in which Fuel Injection ReturnControl End Flag xEtcFEd is set ON.

According to this first embodiment described above, in the system which,when ETC cooperation down-shift is to be performed on the basis of thedriver's intention of deceleration, makes an engine output increasingcontrol for increasing the engine output without depending on thedriver's accelerator operation, a start timing of the engine outputincreasing control (throttle opening control and fuel injection returncontrol) is set at a time point when the real oil pressure estimatedvalue PrealF of the releasing clutch decreases to. an initial oilpressure (a predetermined transfer torque-equivalent oil pressure) orlower. Therefore, in ETC cooperation down-shift, the engine outputincreasing control can be started when the oil pressure of the releasingclutch decreases to a level of not higher than a predetermined transfertorque capacity-equivalent oil pressure at which neither an accelerationfeeling nor a shock occurs even upon starting of the engine outputincreasing control. Thus, the start timing of the engine outputincreasing control can be set with a high accuracy and the driver is notgiven an acceleration feeling or a shock by the engine output increasingcontrol. Besides, since the start timing of the engine output increasingcontrol can be set without depending on the timer, the engine outputincreasing control can be executed by a simple logic configuration andthe setting of reduced parameters. Thus, there also accrues an advantagethat the practical application of the controller is easy.

In this first embodiment, moreover, it is taken into account that aninitial oil pressure which causes neither an acceleration feeling nor ashock even upon starting of the engine output increasing control duringETC cooperation down-shift varies depending on the input torque of thespeed change gear mechanism 55 and the type of the releasing clutch, andthe initial oil pressure is set on the basis of an estimated value ofthe input torque and the type of the releasing clutch. Therefore, aninitial oil pressure not causing an acceleration feeling or a shock canbe set without excess or deficiency in accordance with the input torqueof the shift mechanism and the type of the releasing clutch. Thus, thereis an advantage that the start timing setting accuracy for the engineoutput increasing control can be further improved.

According to this first embodiment described above, in the system which,when performing ETC cooperation down-shift on the basis of the driver'sintention of deceleration, makes an engine output increasing control forincreasing the engine output without depending on the driver'saccelerator operation, the time point at which the down-shift isdetermined to have reached a predetermined substantial end state isdetermined to be an end timing of the engine output increasing control(throttle opening control and fuel injection return control). Therefore,when performing a down-shift on the basis of the driver's intention ofdeceleration, the engine output can be decreased to a proper value (avalue free of output increase) in conformity with the timing at whichthe engaging clutch has come to possess a transfer torque capacitynecessary for completion of the down-shift, and thus it is possible toprevent the occurrence of an unpleasant shock such as a push-out feelingor a deceleration shock at the end of the engine output increasingcontrol.

In this first embodiment, moreover, the shift progress ratio SftRed atthe end of the engine output increasing control (at the start of endcontrol) is set taking into account a response delay of the system atthe end of the engine output increasing control relative to the shiftprogress ratio (SftR=100%) after shift, then upon arrival of the shiftprogress ratio SftR at the shift progress ratio SftRed during the engineoutput increasing control, it is determined that a predetermined statecorresponding to a substantial end of the down-shift has been reached,and the engine output increasing control is ended. Therefore, an endtiming of the engine output increasing control can be set moreappropriately in anticipation of a response delay of the systemassociated with the end of the same control.

Further, since an end timing of the engine output increasing control isdetermined on the basis of a change DSftR of the shift progress ratioSftR [=100×(input shaft rotational speed Nt−output shaft rotationalspeed No×gear ratio before shift)/(output shaft rotational speed No×gearratio after shift−output shaft rotational speed No×gear ratio beforeshift)], i.e., a change in gear ratio (input shaft rotational speedNt/output shaft rotation speed No), it is also possible to compensatefor a change in vehicle speed during a down-shift caused by a change ofthe output shaft rotational speed No, i.e., a change in runningresistance based on a road surface gradient, whether the brakes havebeen applied or not and whether the braking force is large or small.

Further, in this first embodiment, a start timing of the engine outputincreasing control is set at a time point at which the estimated realoil pressure value PrealF of the releasing clutch decreases to aninitial oil pressure (a predetermined transfer torquecapacity-equivalent oil pressure) or lower. Therefore, in ETCcooperation down-shift, the engine output increasing control can bestarted at a time point at which the oil pressure of the releasingclutch decreases to a level of not higher than a predetermined transfertorque capacity-equivalent oil pressure causing neither an accelerationfeeling nor a shock even upon starting of the engine output increasingcontrol. As a result, a start timing of the engine output increasingcontrol can be set with a high accuracy and it is possible to preventthe driver from receiving an acceleration feeling or a shock by theengine output increasing control. Besides, since it is possible to set astart timing of the engine output increasing control without dependencyon the timer, the same control can be performed by a simple logicconfiguration and the setting of reduced parameters, and thus there alsoaccrues an advantage that the practical application of the controller iseasy.

Further, in this first embodiment, it is taken into account that aninitial oil pressure causing neither an acceleration feeling nor a shockeven upon starting of the engine output increasing control during ETCcooperation down-shift varies depending on the input torque of the speedchange gear mechanism 55 and the type of the releasing torque, and theinitial oil pressure is set on the basis of an estimated value of inputtorque and the type of the releasing clutch. Therefore, an initial oilpressure causing neither an acceleration feeling nor a shock can be setwithout excess or deficiency in accordance with the input torque of theshift mechanism and the type of the releasing clutch. Thus, there alsois an advantage that the start timing setting accuracy for the engineoutput increasing control can be further improved.

In this first embodiment, moreover, the response of a real oil pressurerelative to the oil pressure command value for the releasing clutch isapproximated by the transfer characteristic “first order lag +timedelay” and the real oil pressure of the releasing clutch is calculatedby the weighted averaging calculation based on the oil pressure commandvalue. Therefore, the real oil pressure of the releasing clutch can becalculated in an extremely simple manner.

Second Embodiment

Thus, in the above first embodiment the response of a real oil pressurerelative to the oil pressure command value of the releasing clutch isapproximated by the transfer characteristic “first order lag+time delay”and the real oil pressure of the releasing clutch is calculated by theweighted averaging calculation based on the oil pressure command value.But in a second embodiment of the present invention, which isillustrated in FIG. 21, attention is paid to the existence of acorrelation between an electric current value of an oil pressure controlvalve (electromagnetic valve) for controlling the oil pressure of thereleasing clutch and the amount of operation, and hence oil pressure, ofthe oil control valve, then the response of a real oil pressure relativeto a detected electric current value of the oil pressure control valveis approximated by the transfer characteristic “first order lag+timedelay” and a real oil pressure of the releasing clutch is calculated bythe weighted averaging calculation of an oil pressure command value. Inthis second embodiment it is the following processings that aredifferent from the processings in the first embodiment.

-   (1) According to this second embodiment, in Step 143 in the    releasing clutch oil pressure control routine of FIG. 11, an    electric current value of the oil pressure control valve for    controlling the oil pressure of the releasing clutch is detected,    then this detected electric current value is converted to an oil    pressure with use of a map constructed beforehand on the basis of    experiment data or the like or by a mathematical expression, and the    thus-converted oil pressure value is stored as an initial value of    an estimated real oil pressure value Preal of the releasing clutch    in the present stage.-   (2) According to this second embodiment, in Step 221 in the throttle    opening control start determination routine of FIG. 14 and Step 321    in the fuel injection start determination routine of FIG. 19, an    electric current value of the oil pressure control valve is    detected, then this detected electric current value is converted to    an oil pressure Pcon with use of a map or a mathematical expression,    and using this converted oil pressure value Pcon, an estimated real    oil pressure value Preal of the releasing clutch of this time is    calculated by the following weighted averaging operation equation:    Preal=m·Pcon+(1−m)·PrealO

In the above equation, PrealO stands for an estimated real oil pressurevalue of last time and m stands for the weighted averaging coefficient(0<m<1). As an initial value of the estimated real oil pressure valuePreal there is used the foregoing value.

-   (3) According to this second embodiment, in Step 227 in the throttle    opening control start determination routine of FIG. 14 and Step 327    in the fuel injection start determination routine of FIG. 19, as in    the above (2), an estimated real oil pressure value PrealF in the    response delay period is calculated by the following weighted    averaging operation equation:    PrealF=m·Pcon+(1−m)·PrealFO

In the above formula, PrealF stands for an estimated real oil pressurevalue of last time and m stands for the weighted averaging coefficient(0<m<1).

The other processings than the above (1) to (3) are the same as in thefirst embodiment.

Also in this second embodiment it is possible to obtain the same effectas in the first embodiment.

Third Embodiment

In the above first and second embodiments, at the time of performing ETCcooperation down-shift in accordance with the driver's intention ofdeceleration, a start timing of the engine output increasing control(throttle opening control and fuel injection return control) is setequal to the time point when the estimated real oil pressure valuePrealF decreases to an initial oil pressure (a predetermined transfertorque capacity-equivalent oil pressure). But in a third embodiment ofthe present invention illustrated in FIGS. 22 to 31, at the time ofperforming ETC cooperation down-shift, a start timing of the engineoutput increasing control (throttle opening control and fuel injectionreturn control) is set to the earliest one of the following three timepoints T1, T2 and T3:

-   (1) a time point T1 at which it is determined that the oil pressure    of the releasing clutch has decreased to an initial oil pressure (a    predetermined transfer torque capacity-equivalent oil pressure) or    lower during ETC cooperation down-shift;-   (2) a detected time point T2 of a change in gear ratio; and-   (3) an elapsed time point T3 of a set time after the start of shift.

In this case, the set time (T3) after the start of a shift may be apreset constant time for the simplification of control processings. But,for example, as the vehicle speed becomes higher, there is a tendencythat the driver is not given an acceleration feeling or a shock even ifthe start timing of the engine output increasing control is quickened.Therefore, the set time (T3) after the start of shift may be set inaccordance with an operating condition such as the vehicle speed. By sodoing, for example in a down-shift during high-speed running, the engineoutput increasing control can be started in an earlier stage and henceit is possible to quicken the action of engine brake in high-speedrunning.

The following description is now provided about processing contents ofvarious routines used in this third embodiment.

Shifting Oil Pressure Control

A shifting oil pressure control routine of FIG. 22 is executed in thecase where the shift type is ETC cooperation down-shift. Once thisroutine is started, first in Step 401, a releasing clutch oil pressurecontrol routine of FIG. 23 to be described later is executed to controlthe oil pressure of the releasing clutch, then in Step 402 whichfollows, the engaging clutch oil pressure control routine of FIG. 12described above is executed to control the oil pressure of the engagingclutch.

Thereafter, the processing flow advances to Step 403, in which whetherthe down-shift has been completed or not is determined on the basis ofwhether Control Stage Flags 1 and 2 to be described later are equal to 4and 5, respectively. Upon completion of the down-shift, the processingflow advances to Step 404, in which Control Stage Flags 1 and 2 arereset to the initial value “0” and all of other Flags xEtc, xEtcTSt,xEtcFSt, xEtcTEd, xEtcFED, xTSt1, xTSt2, xTSt3, xFSt1, xFSt2 and xFSt3are reset to “OFF” to terminate this routine.

Releasing Clutch Oil Pressure Control

A description will now be given about processing contents of a releasingclutch oil pressure control routine of FIG. 23 which is executed in Step401 in the shifting oil pressure control routine of FIG. 22. Thisroutine corresponds to the addition of a processing of Step 143 abetween Steps 142 and 143 in the releasing clutch oil pressure controlroutine of FIG. 11 described in the first embodiment.

According to this routine, when Control Stage Flag 1 is determined equalto 0 in Step 141 and the first-stage control is executed, Control StageFlag 1 is set to “1” in Step 142, then in Step 143 the initial value ofan estimated real oil pressure value Preal of a releasing clutch isupdated by an oil pressure command value PyDr for the releasing clutch.Thereafter, the processing flow advances to Step 143 a, in which a timerTimDr for measuring an elapsed time after the start of shift is reset,then in the next Step 144 the oil pressure command value for thereleasing clutch is set to a stand-by oil pressure PtDr.

Subsequent processings are the same as in the releasing clutch oilpressure control routine of FIG. 11 described in the first embodiment.

Throttle Opening Control Start Determination

Also in this third embodiment the throttle opening control routine FIG.13 described in the first embodiment is executed and in Step 203 in thesame routine there is executed a throttle opening control startdetermination routine of FIG. 24. First in Step 411, a timer conditiondetermination (throttle) routine of FIG. 25 is executed and it isdetermined whether the time measured by the timer TimDr which is formeasuring an elapsed time after the start of shift is a predeterminedtime T3t or longer (Step 421). If the elapsed time (TimDr) after thestart of shift is the predetermined time T3 or longer, First ThrottleOpening Control Start Determination Flag xTSt1 is set ON, while if theelapsed time (TimDr) after the start of shift is shorter than thepredetermined time T3t, First Throttle Opening Control StartDetermination Flag xTSt1 is kept OFF. The predetermined time T3t may bea preset fixed time for the simplification of control processings, butmay be set using a map or a mathematical expression in accordance withoperating conditions such as vehicle speed and shift position. Forexample, the predetermined time T3t may be set so as to become shorteras the vehicle speed increases or as the shift range becomes higher.

When the timer condition determination (throttle) routine of FIG. 25 isended, the processing flow advances to Step 412 in FIG. 24, in which itis determined whether First Throttle Opening Control Start DeterminationFlag xTSt1 is ON or not. If the Flag is ON, the processing flow advancesto Step 417, in which Throttle Opening Control Start Flag xEtcTSt is setON.

On the other hand, if First Throttle Opening Control Start DeterminationFlag xTSt1 is OFF, the processing flow advances to Step 413, in which achange in gear ratio determination (throttle) routine of FIG. 26 isexecuted and it is determined whether the shift progress ratio SftR(gear ratio) is a predetermined value or larger (Step 431). Since theshift progress ratio SftR is calculated on the basis of both a detectedvalue of the input shaft rotational speed Nt and a detected value of theoutput shaft rotational speed No in the speed change gear mechanism 55,the shift progress ratio SftR varies in the vicinity of “0” due tovariations in both detected values even if a change in gear ratio doesnot occur. Therefore, in Step 431 it is determined whether the shiftprogress ratio SftR is a predetermined value or larger whichpredetermined value somewhat exceeds the range of variations of SftRbefore occurrence of a change in gear ratio. If the shift progress ratioSftR is not lower than the predetermined value, it is determined that achange in gear ratio has occurred, and Second Throttle Opening ControlStart Determination Flag xTSt2 is set ON (Step 432). On the other hand,if the shift progress ratio SftR is lower than the predetermined value,it is determined that a change in gear ratio has not occurred yet, andSecond Throttle Opening Control Start Determination Flag xTSt2 is keptOFF.

When the change in gear ratio determination (throttle) routine of FIG.26 is ended, the processing flow advances to Step 414, in which it isdetermined whether Second Throttle Opening Control Start DeterminationFlag xTSt2 is ON or not. If the Flag is ON, the processing flow advancesto Step 417, in which Throttle Opening Control Start Flag xEtcTSt is setON.

On the other hand, if Second Throttle Opening Control StartDetermination Flag xTSt2 is OFF, the processing flow advances to Step415, in which an initial oil pressure arrival determination (throttle)routine of FIG. 27 is executed and in the same way as in the routine ofFIG. 14 it is determined whether the estimated real oil pressure valuePrealF has decreased to an initial oil pressure (a predeterminedtransfer torque capacity-equivalent oil pressure) or lower. Upondecrease of the estimated real oil pressure value PrealF to the initialoil pressure or lower, the processing flow advances to Step 230, inwhich a delay processing for the time delay Tm in oil pressure responseis performed. Thereafter, the processing flow advances to Step 231 a, inwhich Third Throttle Opening Control Start Determination Flag xTSt3 isset ON. If the estimated real oil pressure value PrealF has notdecreased to the initial oil pressure or lower, Third Throttle OpeningControl Start Determination Flag xTSt3 is kept OFF. The processings ofSteps 221 to 230 in the initial oil pressure arrival determination(throttle) routine of FIG. 27 are the same the processings of Steps 221to 230 in the routine of FIG. 27.

When the initial oil pressure arrival determination (throttle) routineis ended, the processing flow advances to Step 416 in FIG. 24, in whichit is determined whether Third Throttle Opening Control StartDetermination Flag xTSt3 is ON or not. If the Flag is ON, the processingflow advances to Step 417, in which Throttle Opening Control Start FlagxEtcTSt is set ON. On the other hand, if Third Throttle Opening ControlStart Determination Flag xTSt3 is OFF, Throttle Opening Control FlagxEtcTSt is kept OFF.

Fuel Injection Start Determination

Also in this third embodiment the fuel injection return control routineof FIG. 18 described in the first embodiment is executed and in Step 303of the same routine there is executed a fuel injection startdetermination routine of FIG. 28. Once this routine is started, first inStep 451 there is executed a timer condition determination (fuel)routine of FIG. 29 and it is determined whether the time measured by atimer TimDr which is for measuring an elapsed time after the start ofshift is a predetermined time T3f or longer (Step 461). If the elapsedtime (TimDr) is not shorter than the predetermined time T3f, First fuelInjection Start Determination Flag xFSt1 is set ON, while if the elapsedtime (TimDr) has not yet reached the predetermined time T3, First FuelInjection Start Determination Flag xFSt1 is kept OFF. The predeterminedtime T3f may be a preset fixed time for the simplification of controlprocessings, but may be set using a map or a mathematical expression inaccordance with operating conditions such as vehicle speed and shiftposition. For example, the predetermined time T3f may be set so as tobecome shorter as the vehicle speed becomes higher or as the shift rangebecomes higher.

When the timer condition determination (fuel) routine of FIG. 29 isended, the processing flow advances to Step 452 in FIG. 28, in which itis determined whether First Fuel Injection Start Determination FlagxFSt1 is ON or not. If the Flag is ON, the processing flow advances toStep 457, in which Fuel Injection Return Control Start Flag xEtcFSt isset ON.

On the other hand, if First Fuel Injection Start Determination FlagxFSt1 is OFF, the processing flow advances to Step 453, in which achange in gear ratio determination (fuel) routine of FIG. 30 is executedand whether a change in gear ratio has occurred or not is determined onthe basis of whether the shift progress ratio SftR (gear ratio) is apredetermined value of higher which predetermined value somewhat exceedsthe range of variation in the shift progress ration SftR beforeoccurrence of a change in gear ratio (Step 471). As a result, if theshift progress ratio SftR is determined to be not lower than thepredetermined value, it is determined that there occurred a change ingear ratio, and Second Fuel Injection Start Determination Flag xFSt2 isset ON (Step 472). On the other hand, if the shift progress ratio SftRis lower than the predetermined value, it is determined that a change ingear ratio has not occurred yet, and Second Fuel Injection StartDetermination Flag xFSt2 is kept OFF.

When the change in gear ratio determination (fuel) routine of FIG. 30 isended, the processing flow advances to Step 454 in FIG. 28, in which itis determined whether Second Fuel Injection Start Determination FlagxFSt2 is ON or nor. If the Flag is ON, the processing flow advances toStep 457, in which Fuel Injection Return Control Start Flag xEtcFSt isset ON.

On the other hand, if Second Fuel Injection Start Determination FlagxFSt2 is OFF, the processing flow advances to Step 455, in which aninitial oil pressure arrival determination (fuel) routine of FIG. 31 isexecuted and in the same way as in the routine of FIG. 19 describedabove it is determined whether the estimated real oil pressure valuePrealF has decreased to an initial oil pressure (a predeterminedtransfer torque capacity-equivalent oil pressure) or less. Upon decreaseof the estimated real oil pressure value PrealF to the initial oilpressure or less, the processing flow advances to Step 330, in which adelay processing for the time delay Tm in oil pressure response isperformed. Then, the processing flow advances to Step 331 a, in whichThird Fuel Injection Start Determination Flag xFSt3 is set ON. When theestimated real oil pressure value PrealF has not decreased to theinitial oil pressure or less, Third Fuel Injection Start DeterminationFlag xFSt3 is kept OFF. The processings of Steps 321 to 330 in theinitial oil pressure arrival determination (fuel) routine of FIG. 31 arethe same as the processings of Steps 321 to 330 in the routine of FIG.19.

When the initial oil pressure arrival determination (fuel) routine ofFIG. 31 is ended, the processing flow advances to Step 456 in FIG. 28,in which it is determined whether Third Fuel Injection StartDetermination Flag xFSt3 is ON or not. If the Flag is ON, the processingflow advances to Step 457, in which Fuel Injection Return Control StartFlag xEtcFSt is set ON. On the other hand, if Third Fuel Injection StartDetermination Flag xFSt3 is OFF, Fuel Injection Return Control StartFlag xEtcFSt is kept OFF.

In this third embodiment described above, by both the throttle openingcontrol start determination routine of FIG. 24 and the fuel injectionstart determination routine of FIG. 28, a start timing of the engineoutput increasing control (throttle opening control and fuel injectionreturn control) is set to the earliest one of the following three timepoints T1, T2 and T3:

-   (1) a time point T1 at which it is determined that the oil pressure    of the releasing clutch has decreased to an initial oil pressure or    lower during ETC cooperation down-shift;-   (2) a detected time point T2 of a change in gear ratio; and-   (3) an elapsed time pointT3 of a predetermined time after the start    of shift.

According to this construction, the engine output increasing control canbe started in an earlier stage and the engine brake can be allowed toact quickly during a down-shift without causing the driver to receive anacceleration feeling or a shock by the engine output increasing control.Particularly, if the set time (T3) after the start of shift is setaccording to an operating condition such as vehicle speed, then in adown-shift during high-speed running, the engine output increasingcontrol can be started in an earlier stage and the action of enginebrake in high-speed running can be improved.

Fourth Embodiment

In the above first to third embodiments, when the throttle openingcontrol is started, the throttle angle command value is changed up to atarget throttle opening quantity continuously at a stretch, but in afourth embodiment of the present invention illustrated in FIGS. 32 and33, in the period until detection of a change in gear ratio, a controlis made so that the engine output which increases under the engineoutput increasing control changes gradually, and upon detection of achange in gear ratio, the throttle angle command value tangleat ischanged up to a target throttle opening quantity.

The throttle opening control of this fourth embodiment is executed by athrottle opening control routine of FIG. 33. This routine corresponds tothe addition of two steps 211 and 212 to the throttle opening controlroutine of FIG. 13 described in the first embodiment and the processingsof the other Steps 201 to 210 are the same as in the first embodiment.

In this fourth embodiment, after the start of ETC cooperation down-shiftcontrol, if the estimated real oil pressure value PrealF of thereleasing clutch decreases to a level of not higher than the initial oilpressure and Throttle Opening Control Start Flag xEtcTSt is set ON, theprocessing flow advances like Steps 201→203→205→211 at every starting ofthe routine of FIG. 33, then in Step 211 it is determined if the shiftprogress ratio SftR is not lower than a predetermined value whichsomewhat exceeds the range of variations in the shift progress ratioSftR before occurrence of a change in gear ratio. If the shift progressratio SftR is lower than the predetermined value, it is determined thata change in gear ratio has not occurred, and the processing flowadvances to Step 212, in which the throttle angle command value tangleatis corrected so as to increase gradually on a predetermined quantityatanglea basis to open the throttle position gradually, causing theengine output to increase gradually. This gradual change control iscontinued until the shift progress ratio SftR reaches a predeterminedvalue (until a change in gear ratio is detected).

Thereafter, upon arrival of the shift progress ratio SftR at thepredetermined value and detection of a change in gear ratio, theprocessing flow advances from Step 211 to Step 209, in which thethrottle angle command value tangleat (throttle opening quantity) is setusing a throttle opening quantity setting map of FIG. 17 and inaccordance with a to-be-down-shifted range and water temperature and theinput shaft rotational speed Nt. The control which follows is the sameas in the first embodiment.

According to this fourth embodiment, in the period after start of thethrottle opening control until detection of a change in gear ratio, acontrol is made so that the engine output which increases under theengine output increasing control increases gradually. Therefore, it ispossible to make a transfer to a state of slip and the start of a changein gear ratio can be more quickened while suppressing an accelerationfeeling and a push-out shock which occur as a result of increasing theengine output in a period in which the releasing clutch still possessesa sufficient transfer torque capacity.

Fifth Embodiment

In the above first to fourth embodiments an estimated real oil pressurevalue of a releasing clutch is calculated by the weighted averagingcalculation of an oil pressure command value for a releasing clutch or adetected electric current value (operation quantity) of the oil pressurecontrol valve and then on the basis of the estimated real oil pressurevalue there is estimated a time point at which the oil pressure of thereleasing clutch decreases to a level of not higher than the initial oilpressure (a predetermined transfer torque capacity-equivalent oilpressure). However, in a fifth embodiment of the present inventionillustrated in FIGS. 34 to 36, the oil pressure of a releasing clutch isestimated by utilizing the output of an oil pressure switch which isprovided as fail detecting means for the oil pressure control valve forcontrolling the oil pressure of each releasing clutch, and a time pointcorresponding to a decrease in oil pressure of the releasing clutch to alevel of not higher than the initial oil pressure (a predeterminedtransfer torque capacity-equivalent oil pressure) is estimated.

The oil pressure switch is constructed so as to turn ON (Hi output) whenthe real oil pressure is not lower than a threshold value and turn OFF(Lo output) when the real oil pressure is lower than the thresholdvalue. A defective clutch is detected by determining whether the output(real oil pressure) of the oil pressure switch and an oil pressurecommand value are in a proper relation or not.

According to this fifth embodiment, in the routines of FIGS. 35 and 36,when calculating an estimated real oil pressure value of a releasingclutch by the weighted averaging calculation based on an oil pressurecommand value PyDr for a releasing clutch and when the output PSWy ofthe oil pressure switch changes from ON to OFF, an ON→OFF switchingthreshold value (set oil pressure) of the oil pressure switch isinputted to the estimated real oil pressure value of the releasingclutch.

A throttle opening control start determination routine of FIG. 35corresponds to the addition of two Steps 221 a and 221 b between Steps221 and 222 in the throttle opening control start determination routineof FIG. 14 described in the first embodiment and deletion of the delayprocessing of Step 230. Once this routine is started, an estimated realoil pressure value Preal of a releasing clutch (y) to be controlled forrelease by ETC cooperation down-shift of this time is calculated by theweighted averaging calculation based on an oil pressure command valuePyDr for the releasing clutch (y), then the processing flow advances toStep 221 a, in which it is determined whether the present state is astate just after switching from ON to OFF of the output PSWy of the oilpressure switch which is for detecting the oil pressure of the releasingclutch (y). If the answer is negative, the processing flow advances toStep 222, in which the estimated real oil pressure value Prealcalculated in Step 221 is stored as an initial value of the estimatedreal oil pressure value PrealF in the response delay period.

Upon subsequent switching from ON to OFF of the output PSWy of the oilpressure switch, the processing flow advances from Step 221 a to Step221 b, in which an ON→OFF switching threshold value (set oil pressure)of the oil pressure switch is inputted to the estimated real oilpressure value Preal of the releasing clutch. Then, in the next Step222, this estimated real oil pressure value Preal is stored as aninitial value of the estimated real oil pressure value PrealF in theresponse delay period. Subsequent processings are the same as in thethrottle opening control start determination routine of FIG. 14.However, since the time point of arrival of the real oil pressure at thepredetermined oil pressure through a time delay relative to the oilpressure command is detected by the oil pressure switch, such a delayprocessing as Step 230 in FIG. 14 is not necessary.

A fuel injection start determination routine of FIG. 36 corresponds tothe addition of two Steps 321 a and 321 b between Steps 321 and 322 inthe fuel injection start determination routine of FIG. 19 and deletionof the delay processing of Step 330. Once this routine is started, firstin Step 321, an estimated real oil pressure value Preal of a releasingclutch (y) to be controlled for release by ETC cooperation down-shift ofthis time is calculated by an oil pressure command value PyDr of thereleasing clutch (y). Thereafter, the processing flow advances to Step321 a, in which it is determined whether the present state is a statejust after switching from ON to OFF of the output PSW of an oil pressureswitch which is for detecting the oil pressure of the releasing clutch(y). If the answer is negative, the processing flow advances to Step322, in which the estimated real oil pressure Preal calculated in Step321 is stored as an initial value of the estimated real oil pressurevalue PrealF in the response delay period.

Thereafter, upon switching from ON to OFF of the output PSWy of the oilpressure switch, the processing flow advances from Step 321 a to Step321 b, in which an ON→OFF switching threshold value (set oil pressure)of the oil pressure switch is inputted to the estimated real oilpressure value Preal of the releasing clutch. Then, in Step 322 whichfollows, this estimated real oil pressure value is stored as an initialvalue of the estimated real oil pressure value PrealF in the responsedelay period. Subsequent processings are the same as in the fuelinjection start determination routine of FIG. 19 described above.However, since the time point of arrival of the real oil pressure at thepredetermined oil pressure through a time delay relative to the oilpressure command is detected by the oil pressure switch, such a delayprocessing as Step 330 in FIG. 19 is not necessary.

Since in this fifth embodiment described above the estimated real oilpressure value Preal calculated by the weighted averaging calculation ofthe oil pressure command value PyDr of the releasing clutch is correctedby utilizing the output of the oil pressure switch, the oil pressure canbe estimated with a high accuracy by utilizing the output of the oilpressure switch which also serves as fail detecting means in the oilpressure control means, thus giving rise to an advantage that the timepoint of decrease of the oil pressure of the releasing clutch to a levelof not higher than the initial oil pressure can be estimated moreaccurately.

Sixth Embodiment

There is a system provided with, other than the oil pressure switch, anoil pressure sensor able to detect an oil pressure continuously. Thefifth embodiment of the present invention shown in FIGS. 37 and 38 maybe applied to the system provided with the oil pressure sensor and anoil pressure Pseny detected by the oil pressure sensor may be used as aninitial value of the estimated real oil pressure value PrealF in theresponse delay period.

A throttle opening control start determination routine of FIG. 37corresponds to replacing the processing of Step 221 in the throttleopening control start determination routine of FIG. 14 described in thefirst embodiment by Step 220 and deletion of the delay processing ofStep 230. Other processings are the same as in FIG. 14.

A fuel injection start determination routine of FIG. 38 corresponds toreplacing the processing of Step 321 in the fuel injection startdetermination routine of FIG. 19 by Step 320 and deletion of the delayprocessing of Step 230. Other processings are the same as in FIG. 19.

Once the routines of FIGS. 37 and 38 are stated, first in Steps 220 and320, an oil pressure Pseny detected by an oil pressure sensor which isfor detecting the oil pressure of a releasing clutch (y) to becontrolled for release by ETC cooperation down-shift of this time isinputted to an oil pressure value Preal of the releasing clutch (y).Then, in the next Steps 221 and 322, the oil pressure value Preal isstored as an initial value of the estimated real pressure value PrealFin the response delay period. Subsequent processings are the same as inthe first embodiment. However, since the real oil pressure is monitoredby the oil pressure sensor, it is not necessary to perform suchdelay-based time delay processings as Steps 230 and 330 in FIGS. 14 and19.

As to the estimated real oil pressure value PrealF in the response delayperiod which is calculated in Steps 226 to 228 and 326 to 328, since itpredicts a future oil pressure, the estimated real oil pressure valuePrealF in the response delay period is calculated by the weightedaveraging calculation of the oil pressure command value PyDr as in thefirst embodiment, etc.

This sixth embodiment described above is also advantageous in that thetime point of decrease of the oil pressure of the releasing clutch to alevel of not higher than the initial oil pressure can be estimated witha high accuracy by utilizing the output of the oil pressure sensor whichalso serves as fail detecting means in the oil pressure control means.

Seventh Embodiment

In the first embodiment, the shift progress ratio SftRed at the end ofthe engine output increasing control (at start of end control) is settaking into account the response delay of the system related to the endof the engine output increasing control relative to the gear ratio(SftR=100%) after shift, then upon arrival of the shift progress ratioSftR at the shift progress ratio SftRed in the engine output increasingcontrol, it is determined that a predetermined state corresponding to asubstantial end of the down-shift has been reached, and the engineoutput increasing control is ended. In a seventh embodiment of thepresent invention shown in FIGS. 39 to 41, it is taken into account thatthe end of a down-shift can be determined at a time point at which theinput shaft rotational speed Nt of the speed change gear mechanism 55 indown-shift reaches an after-shift synchronous rotational speed Nttdetermined from both output shaft rotational speed No and the gear ratioafter shift. In view of this point, when the input shaft rotationalspeed Nt, in the engine output increasing control, has reached arotational speed lower by a predetermined amount DNted which is set inconsideration of a system response delay related to the end of theengine output increasing control relative to the after-shift synchronousrotational speed Ntt [in other words, when a deviation DNt (=Ntt−Nt)between the input shaft rotational speed Nt and the after-shiftsynchronous rotational speed Ntt has become the predetermined amountDNted or less], it is determined that a predetermined statecorresponding to a substantial end of the down-shift has been reached,and the engine output increasing control is ended.

The following description is now provided about processing contents ofroutines of FIGS. 40 and 41 which are executed in this seventhembodiment. Other routines are the same as in the first embodiment.

Throttle Opening Control End Determination

When a throttle opening control end determination routine of FIG. 40 isstarted, first in Step 1401, there are calculated, in the same way as inthe first embodiment, a response delay (Td) of a full closing motion ofthe throttle valve 15, a response delay (Te) in the period after actualfull closing of the throttle valve 15 until actual disappearance of anincrease of engine output, and time (Tsd) required after enddetermination until decrease of the throttle opening command value to“0.”

Thereafter, the processing flow advances to Step 1402, in which athreshold value DNted for throttle opening control end determination(for end control start determination) relative to a deviation(hereinafter referred to as “input shaft rotational speed deviation”)between the after-shift synchronous rotational speed Ntt and the inputshaft rotational speed Nt is calculated by the following equation:DNted=DDNt×(Td+Te+Tsd)/tsmp

In the above equation, DDNt stands for a change quantity (last timevalue−this time value of DDNt) per calculation cycle of the deviationDNt between the after-shift synchronous rotational speed Ntt and theinput shaft rotational speed Nt, and tsmp stands for a calculationcycle. The threshold value DNted for throttle opening control enddetermination (for end control start determination) is set in accordancewith the above equation and taking into account a response delay(Td+Te+Tsd) of the system related to the end of the throttle openingcontrol.

Thereafter, the processing flow advances to Step 1403, in which it isdetermined whether the present input shaft rotational speed deviationDNt (=Ntt−Nt) is not larger than the threshold value DNted. If the inputshaft rotation speed deviation DNt has not reached the threshold valueDNted yet, this routine is ended. Upon arrival of the deviation DNt atthe threshold value DNted, it is determined that a predetermined statecorresponding to a substantial end of the down-shift has been reached,then the processing flow advances to Step 1404, in which ThrottleOpening Control End Flag xEtcTEd is set ON.

Fuel Injection End Determination

When a fuel injection end determination routine of FIG. 41 is started,first in Step 1411, a response delay (Tf) in the period after resumingof fuel cut until disappearance of engine output is calculated in thesame way as in the first embodiment.

Thereafter, the processing flow advances to Step 1412, in which athreshold value DNted for throttle opening control end determination(for end control start determination) relative to the input shaftrotational speed deviation DNt (=Ntt−Nt) is calculated by the followingequation:DNted=DDNt×Tf/tsmp

A threshold value DNted for fuel injection return control enddetermination (for end control start determination) is set in accordancewith the above equation and in consideration of the response delay (Tf)of the system related to the end of fuel injection return control.

Subsequently, the processing flow advances to Step 1413, in which it isdetermined whether the present input shaft rotational speed deviationDNt (=Ntt−Nt) has become the threshold value DNted or less. If the inputshaft rotational speed deviation DNt has not reached the threshold valuedNted yet, this routine is ended. Upon arrival of the input shaftrotational speed deviation DNt at the threshold value DNted, it isdetermined that a predetermined state corresponding to a substantial endof the down-shift has been reached, then the processing flow advances toStep 1414, in which Fuel Injection Return Control End Flag xEtcFEd isset ON.

Also in this seventh embodiment described above it is possible to obtainthe same effect as in the first embodiment.

Eighth Embodiment

In an eighth embodiment of the present invention illustrated in FIGS. 42and 43, it is taken into account that the end of a down-shift can bedetermined when the transfer torque capacity of an engaging clutch whichis controlled for engagement in the down-shift has reached a dividedtorque-equivalent value after shift. In view of this point, when thetransfer torque capacity of the engaging clutch which is controlled forengagement in the engine output increasing control has reached atransfer torque capacity lower by a predetermined amount which is set inconsideration of a response delay of the system associated with the endof the engine output increasing control relative to the dividedtorque-equivalent value after shift, it is determined that apredetermined state corresponding to a substantial end of the down-shifthas been reached, and the engine output increasing control is ended.

The following description is now provided about processing contents ofroutines of FIGS. 42 and 43 which are executed in this eighthembodiment. Other routines are the same as in the first embodiment.

Throttle Opening Control End Determination

When a throttle opening control end determination routine of FIG. 42 isstarted, first in Steps 1501 and 1502, a threshold value DNted forthrottle opening control end determination (for end control startdetermination) is calculated in the same way as in the seventhembodiment and taking into account a response delay (Td+Te+Tsd) of thesystem related to the end of throttle opening control. Then, theprocessing flow advances to Step 1503, in which it is determined whetherthe present input shaft rotational speed deviation DNt (=Ntt−Nt) hasbecome the threshold value DNted or less. If the input shaft rotationalspeed deviation DNt has not reached the threshold value DNted yet, thisroutine is ended.

Then, upon arrival of the input shaft rotational speed deviation DNt atthe threshold value DNted, the processing flow advances to Step 1504, inwhich an oil pressure threshold value PyAped for end determinationrelated to an engaging clutch (y) now under control for engagement iscalculated by the following equation:PyAped=PyApT−DPyAp×(Td+Te+Tsd)/tsmpp

In the above equation, PyApT stands for an oil pressure-equivalent valueat which the transfer torque capacity of the engaging clutch becomes adivided torque value after shift or more, DPyAp stands for a changequantity (this time value - last time value of PyAp) per calculationcycle of the oil pressure PyAp of the engaging clutch (y), and tsmppstands for a calculation cycle of DPyAp. A threshold value PyAped forthe oil pressure PyAp of the engaging clutch (y) at the end of throttleopening control is set in accordance with the above equation and inconsideration of the response delay (Td+Te+Tsd) of the system associatedwith the end of throttle opening control.

Thereafter, the processing flow advances Step 1505, in which it isdetermined whether the oil pressure PyAp of the engaging clutch (y) hasreached a level of not lower than the oil pressure threshold value PyApfor end determination. If the oil pressure PyAp has not yet reached theoil pressure threshold value PyAped, this routine is ended. Upon arrivalof the oil pressure PyAp at the threshold value PyAped, it is determinedthat a predetermined state corresponding to a substantial end of thedown-shift has been reached, and the processing flow advances to Step1506, in which Throttle Opening Control End Flag xEtcTEd is set ON.

As the oil pressure PyAp of the engaging clutch (y) there may be used anestimated value obtained by the weighted averaging calculation of an oilpressure command value for example or there may be used a value detectedby the oil pressure sensor.

Fuel Injection End Determination

When a fuel injection end determination routine of FIG. 43 is started,first in Steps 1511 and 1512, a threshold value DNted for fuel injectionreturn control end determination (for end control start determination)is calculated in the same way as in the seventh embodiment and inconsideration of a response delay (Tf) of the system related to the endof the fuel injection return control. Then, the processing flow advancesto Step 1513, in which it is determined whether the present input shaftrotational speed deviation DNt (=Ntt−Nt) has become the threshold valueDNted or less. If the input shaft rotational speed deviation DNt has notreached to the threshold value DNted yet, this routine is ended.

Upon arrival of the input shaft rotational speed deviation DNt at thethreshold value DNted, the processing flow advances to Step 1514, inwhich an oil pressure threshold value PyAped for end determinationrelated to an engaging clutch (y) now under control for engagement iscalculated by the following equation:PyAped=PyApT−DPyAp×Tf/tsmpp

In the above equation, PyApT stands for an oil pressure-equivalent valueat which the transfer torque capacity of the engaging clutch becomes adivided torque after shift or more, DPyAp stands for a change quantity(this time value−last time value of PyAp) per calculation cycle of theoil pressure PyAp of the engaging clutch (y), and tsmpp stands for acalculation cycle if DPyAp. A threshold value PyAped for the oilpressure PyAp of the engaging clutch (y) at the end of the fuelinjection return control is set in accordance with the above equationand in consideration of the response delay (Tf) of the system related tothe end of the fuel injection return control. Thereafter, the processingflow advances to Step 1515, in which it is determined whether the oilpressure PyAp of the engaging clutch (y) has become the oil pressurethreshold value PyAped for end determination or more, and if the oilpressure PyAp has not reached the threshold value PyAped yet, thisroutine is ended. Then, upon arrival of the oil pressure PyAp at thethreshold value PyAped, it is determined that a predetermined statecorresponding to a substantial end of the down-shift has been reached,and the processing flow advances to Step 1516, in which Fuel InjectionReturn Control End Flag xEtcFEd is set ON.

In this eighth embodiment described above, since en end timing of theengine output increasing control is determined using both the inputshaft rotational speed deviation DNt and the oil pressure PyAp of theengaging clutch, there accrues an advantage that the end timing of theengine output increasing control can be determined more accurately.

The present invention is not limited to the above first, seventh andeighth embodiments, but may be constructed as follows for example.

-   (1) An end timing of a down-shift in the engine output increasing    control, (hereinafter referred to as “predictive down-shift end    timing”), is predicted, and relative to the predictive down-shift    end timing, a timing which is earlier by a predetermined time is set    taking into account a response delay of the system related to the    end of the engine output increasing control, then upon arrival of    the said earlier timing it is determined that a predetermined state    corresponding to a substantial end of the down-shift has been    reached, and the engine output increasing control is ended.-   (2) During the engine output increasing control, it is predicted at    what timing the input shaft rotational speed reaches a predictive    after-shift synchronous rotational speed which is determined from    both output shaft rotational speed and a gear ratio after shift,    (the said timing will hereinafter be referred to as “predictive    synchronous timing”), and relative to this predictive synchronous    timing, a timing which is earlier by a predetermined time is set    taking into account a response delay of the system related to the    end of the engine output increasing control, then upon arrival at    the said earlier timing it is determined that a state corresponding    to a substantial end of a down-shift has been reached, and the    engine output increasing control is ended.-   (3) A threshold value for determining a predetermined state    corresponding to a substantial end of a down-shift may be set taking    the vehicle body deceleration also into account. By so doing, even    when the vehicle speed changes, with a change in after-shift    synchronous rotational speed and a consequent change of shift time,    due to a change in running resistance based on a road surface    gradient or depending on whether a braking operation has been    performed or not or whether a brake operating force is large or    small, it is possible to let the engine output increasing control be    ended properly.

Although in the above embodiments the engine output increasing controlis effected by both throttle opening control and fuel injection returncontrol, even by the addition of a fuel quantity increasing control oran ignition delay control to the engine output increasing control, or byreplacing both throttle opening control and fuel injection returncontrol with an fuel quantity increasing control or an ignition delaycontrol, the engine output increasing control can be effected in the wayof thinking as above. Further, although the above embodiments areconcerned with a gasoline engine, also in a diesel engine, the presentinvention can be effected by performing a fuel injection quantityincreasing control as the engine output increasing control.

Ninth Embodiment

Next, a control example in ETC cooperation down-shift according to anninth embodiment of the present invention will be described withreference to FIG. 44. At a time point t0 at which an ETC cooperationdown-shift execution condition exists and a down-shift command isoutputted, an oil pressure command value for a releasing clutch isdecreased rapidly to a stand-by oil pressure PtDr (a little lower oilpressure than the set load-equivalent oil pressure PsDr of the returnspring of the releasing clutch). A subsequent state is held to a statejust before development of an engaging force of the releasing clutchunder the stand-by oil pressure PtDr. This is for the purpose of notonly promoting the increase of the input shaft rotational speed Nt bythe engine output increasing control but also suppressing a vehiclerush-out feeling caused by the engine output increasing control.

Also in this ETC cooperation down-shift, an oil pressure control for anengaging clutch is almost the same as in power ON down-shift. At anoutput time point t0 of a down-shift command, an oil pressure commandvalue for the engaging clutch is set to a predetermined fill oilpressure Po and a fill control for filling the engaging clutch withworking oil is executed. The fill control is continued for apredetermined time tF, and upon arrival at a state just beforedevelopment of an engaging force of the engaging clutch, the oilpressure command value for the engaging clutch is decreased to astand-by oil pressure PtAp (near the set load-equivalent oil pressurePsAp of the return spring of the engaging clutch) and the fill controlis terminated. A subsequent state is held to a state in which theengaging force of the engaging clutch develops a desired engine brakefeeling under its stand-by oil pressure PtAp. As to the subsequentpressure increasing control, the same processing as in the foregoingpower ON down-shift is performed.

This ETC cooperation down-shift is characteristic in that the engineoutput increasing control is executed in the following manner. In thecourse of decrease of a real oil pressure of the releasing clutch downto the stand-by oil pressure PtDr, at a time point t6 of decrease to“initial oil pressure” at which the transfer torque capacity of thereleasing clutch becomes small or zero and an acceleration feeling isnot created even with an increase of the engine output, the engineoutput increasing control is started.

In this case, for estimating the time point t6 at which the real oilpressure of the releasing clutch decreases to the initial oil pressureor lower, the response of the real oil pressure to the oil pressurecommand value of the releasing clutch is approximated by the transfercharacteristic of “first order lag+time delay,” then an estimated valueof the real oil pressure calculated on the basis of the said transfercharacteristic is compared with the aforesaid initial oil pressure, andat the time point t6 at which the estimated real oil pressure valuedecreases to the initial oil pressure, it is determined that a starttiming of the engine output increasing control has been reached.

At the time point t6 at which the start timing of the engine outputincreasing control is thus determined, a target throttle opening iscalculated by a method to be described later and a throttle openingcontrol is started, then at a somewhat later time point t7 Fuel Cut Flag(“F/C Flag” hereinafter) is turned OFF, a fuel injection return controlis started and the injection of fuel is resumed.

The engine output increases through a predetermined delay after thestart of the engine output increasing control (both throttle openingcontrol and fuel injection return control). As engine output increasedelay factors there are, in connection with the throttle openingcontrol, a response delay (Ta) of an opening motion of the throttlevalve 15 and a response delay (Tb) in the period after actual opening ofthe throttle valve 15 until increase of the engine output, while inconnection with the fuel injection return control there is a responsedelay (Tc) in the period after resuming of fuel injection until increaseof the engine output.

The response delay (Ta) of an opening motion of the throttle valve 15 iscalculated using a map of parameters (e.g., cooling water temperatureand battery voltage) associated with the drive responsivity of the motor17 in the electronic throttle system. The response delay (Tb) in theperiod after opening of the throttle valve 15 until increase of theengine output is calculated using a delay in the period afterintroduction of intake air in an amount increased by opening of thethrottle valve 15 into a cylinder and a map of parameters (e.g., enginespeed and throttle angle) associated with intake air flow velocity. Theresponse delay (Tc) in the period after resuming of fuel injection untilincrease of the engine output is set on the basis of time (time T720° CArequired for the crank shaft to rotate 720° CA) after fuel injectionuntil combustion.

Once the start of control is determined by the start timingdetermination in the throttle opening control (engine output increasingcontrol) described above, a target throttle angle which is set so as toafford such an input shaft rotational speed Nt behavior as attainsdesired shift time and shift feeling is outputted and held. The targetthrottle angle is set on the basis of friction loss of the engine 11,detection results of parameters [e.g., shift pattern (change in gearratio), cooling water temperature, and input shaft rotational speed Nt],and a desired shift time. Further, by changing the target throttle anglein accordance with the magnitude of a road surface gradient and that ofdeceleration of the vehicle body, the feeling can be matched moreminutely to a desired state. In this case, the target throttle angle isset small during deceleration and large during acceleration. The targetthrottle angle is corrected by the output of the air flow meter 14. As aresult, the input shaft rotational speed Nt (output shaft rotationalspeed of the torque converter 52) of the speed change gear mechanism 55begins to increase upon arrival of the oil pressure of the releasingclutch at the stand-by oil pressure PtDr or thereabouts.

During execution of the engine output increasing control, apredetermined engine output increase quantity is held while making anend determination for terminating the actual increase of engine outputby the engine output increasing control in conformity with a time point(a 100% time point of the shift progress ratio SftR) corresponding tothe final down-shift end. In this end determination, a response delay inthe period after the issuance of an end command until actualdisappearance of an increase of engine output is taken into account onthe basis of the shift progress ratio SftR and a change quantity ASftRper unit time AT of the shift progress ratio, then to which value of theshift progress ratio SftR a control end timing capable of offsetting thesaid response delay corresponds is calculated, then whether apredetermined state corresponding to a substantial end of the down-shifthas been reached or not is determined on the basis of whether the shiftprogress ratio SftR has exceeded the calculated value or not, and an endtiming (t8) of both throttle opening control and fuel injection returncontrol, as the engine output increasing control, is determined. If theend timing (t8) is determined, then in the throttle opening control, anend control is executed for decreasing the target throttle angle to “0.”In the end control, a throttle opening control command value isdecreased to “0” with a predetermined gradient in order to ensure atransient reproducibility of the electronic throttle. In the fuelinjection return control, F/C Flag is returned to ON in accordance withthe end determination to resume fuel cut. But this does not apply whenthe request for fuel cut from the engine 11 side has vanished due to asudden decrease of the engine speed or by any other cause.

As response delay factors related to the end of engine output increasethere are, in connection with the throttle opening control, a responsedelay (Td) of a full closing motion of the throttle valve 15, a responsedelay (Te) in the period after actual full closing of the throttle valve15 until actual disappearance of an increase of engine output, and time(Tsd) in the period after end determination until decrease of the targetthrottle angle to “0,” while in connection with the fuel injectionreturn control there is a response delay (Tf) in the period afterresuming of fuel cut until disappearance of the engine output.

The response delay (Td) of a closing motion of the throttle valve 15 iscalculated using a map of parameters (e.g., cooling water temperatureand battery voltage) associated with the drive responsivity of the motor17 in the electronic throttle system. The response delay (Te) in theperiod after full closing of the throttle valve 15 until disappearanceof an increase of engine output is calculated using a delay in theperiod after introduction f of intake air in an amount decreased by fullclosing of the throttle valve into a cylinder until combustion and a mapof parameters (e.g., engine speed and throttle angle) associated withthe intake air flow velocity. The time (Tsd) after end determinationuntil decrease of a target throttle angle to “0” is calculated on thebasis of a target throttle angle decreasing gradient. The response delay(Tf) in the period after resuming of fuel cut until disappearance of theengine output is set on the basis f time (time T720° CA required for thecrank shaft to rotate 720° CA) after resuming of fuel cut until arrivalof the fuel-cut cylinder at a combustion stroke.

In this ninth embodiment, as described above, at a time point t8 atwhich the shift progress ratio SftR reaches a predetermined value E,during execution of the engine output increasing control (both throttleopening control and fuel injection return control), an end control forthe engine output increasing control is started and the target throttleangle is decreased to “0” with a predetermined gradient, then theresponse delays Tsd, Td, Te and Tf are calculated to predict a timepoint t10 at which the engine output disappears by the end control, andon the basis of the time point t10, the time point t9 of resuming fuelcut is predicted taking into account the response delay (Tf) in theperiod after resuming of fuel cut until disappearance of the engineoutput. Upon arrival at the time point t9, F/C Flag is returned ON toresume fuel cut.

On the other hand, as to the oil pressure command value for thereleasing clutch, it is decreased with a constant gradient at a timepoint of arrival of the shift progress ratio SftR at 100%. The ETCcooperation down-shift is completed by such control.

A description will now be given about a method for setting an outputincrease control quantity (target throttle angle) by the engine outputincreasing control. In this ninth embodiment, a target throttle angletangleat is set so that an engine torque (required torque Te)corresponding to a desired engine speed change rate dNe/dt during theengine output increasing control. More specifically, the followingcalculation is performed. As shown in FIG. 47, first the engine speedchange rate dNe/dt is calculated and then multiplied by an engine-sideinertia le to obtain a required torque Te.Te=Ie×dNe/dt

The above equation may be substituted by the following equation tocalculate the required torque Te:Te=Ie×{Ne0×(gr2/gr1)/Tt}gr1: gear ratio before shift

-   -   gr2: gear ratio after shift    -   Tt: target shift time    -   Ie: engine-side inertia    -   Ne0: engine speed at time t0

Thereafter, a map for calculation of a throttle angle change quantitydTAO with engine speed ne and required torque Te as parameters isretrieved and a required throttle angle change quantity dTAOproportional to a target engine speed Ne and required torque Te at everymoment is calculated.

Then, the required throttle angle change quantity dTAO is subjected to aresponse delay compensation processing, taking into account a responsedelay in the period after output of the target throttle angle tanleat tothe electronic throttle system until actual increase or decrease of theamount of intake air and increase or decrease of the engine output, toobtain a required throttle angle change rate dTAO′ as a responsedelay-compensated value. Thereafter, the required throttle angle changequantity dTAO′ after the response delay compensation is added to thetarget throttle angle tangleat of last time to obtain a target throttleangle tangleat of this time.

In this case, in a down-shift involving execution of the engine outputincreasing control, as compared with a down-shift not involvingexecution of the same control, it is preferable to promote a decrease inworking oil pressure of a releasing clutch and/or promote an increase inworking oil pressure of an engaging clutch. By so doing, in thedown-shift involving execution of the engine output increasing control,it is possible to promote the progress of the shift and hence possibleto shorten the shift time.

The shift control according to this ninth embodiment described above isperformed in various routines by cooperation of both AT-ECU 70 andengine ECU 25. The various routines are the same as in the firstembodiment except the following routines, and explanations of portionscommon to the first embodiment will be omitted.

Throttle Opening Control

A throttle opening control routine of FIG. 45 is a subroutine which isexecuted in Step 103 in the shift control routine of FIG. 8, playing arole as engine output increasing control means recited in the appendedclaims.

Once this routine is started, first in Step 2201, it is determinedwhether Throttle Opening Control Start Flag xEtcTSt is OFF which means astate before start of the throttle opening control. If the Flag is OFF,the processing flow advances to Step 2203, in which the throttle openingcontrol start determination routine of FIG. 14 is executed and it isdetermined whether a throttle opening control start timing has beenreached or not. Then, Throttle Opening Control Start Flag xEtcTSt is setor reset in accordance with the result of the determination.

Thereafter, the processing flow advances to Step 2205, in which it isdetermined whether Throttle Opening Control Start Flag xEtcTSt remainsOFF or not. If the Flag remains OFF, the processing flow advances toStep 2207, in which a stored value GaB of the intake air quantity beforestart of the throttle opening control is updated by the present value Gadetected by the air flow meter 14 and this routine is ended.

The other steps in FIG. 45 are the same as the steps shown in FIG. 13.

Target Throttle Angle Calculation

A target throttle angle calculation routine of FIG. 46 is a subroutinewhich is executed in Step 2209 in the throttle opening control routineof FIG. 45. Once this routine is started, first in Step 2260, the enginespeed at time t0 detected on the basis of a pulse interval of outputpulses from the crank angle sensor 24 is inputted and in the next Step2261 there is calculated a target change waveform Ne of the engine speedin a shift period which is determined from a requested value of shiftresponse time. In Step 2262 which follows, an engine speed change ratedNe/dt which is a time differential value of a target change waveform Neis calculated. Then, the processing flow advances to Step 2263, in whichthe engine speed change rate dNe/dt is multiplied by an engine-sideinertia le to obtain a required torque T.Te=Ie×dNe/dt

Thereafter, the processing flow advances to Step 2264, in which a mapfor calculation of a required throttle angle change quantity dTAO withengine speed Ne and required torque Te as parameters is retrieved and arequired throttle angle change quantity dTAO proportional to the presentengine speed Ne and required torque Te is calculated.

Then, the processing flow advances to Step 2265, in which the requiredthrottle angle change quantity dTAO is subjected to a response delaycompensation processing while taking into account a response delay inthe period after output of a target throttle angle tangleat to theelectronic throttle system until actual increase or decrease of theintake air quantity with consequent increase or decrease of the engineoutput, to obtain a required throttle angle change quantity dTAO′ as aresponse delay-compensated value. Thereafter, the processing flowadvances to Step 2266, in which the required throttle angle changequantity dTAO′ after the response delay compensation is added to thetarget throttle angle tangleat of last time to obtain a target throttleangle tangleat of this time.

Target Throttle Angle Compensation Control

A target throttle angle correction control routine of FIG. 57 is asubroutine which is executed in Step 2210 in the throttle openingcontrol routine of FIG. 45. Once this routine is started, first in Step2251, it is determined whether an execution condition for a throttleopening quantity correction control exists or not. For example, theexecution condition is determined on the basis of whether an elapsedtime after the issuance of a throttle opening command is a responsedelay-equivalent time or longer. If the elapsed time after the issuanceof the throttle opening command is shorter than the responsedelay-equivalent time, the execution condition for the throttle openingquantity correction control is not established and this routine isended. Upon subsequent arrival of the elapsed time after the issuance ofthe throttle opening command at the response delay-equivalent time or alonger time, the execution condition for the throttle opening quantitycorrection control becomes valid and the processing flow advances toStep 2252, in which the target throttle angle tangleat is corrected bythe following equation:tangleat=tangleat×DGaT/(Ga−GaB)

In the above equation, DGaT stands for a target value of the intake airquantity Ga, which value is set using a table or the like in accordancewith the target throttle angle tangleat and GaB stands for an intake airquantity just before start of the throttle opening control which hasbeen stored in Step 2207 in the throttle opening control routine of FIG.45. Variations in system fabrication, variations caused by secularchange and variations caused by operating conditions such as atmosphericpressure and intake air temperature are corrected by correcting thetarget throttle angle tangleat in accordance with the above equation.

According to this ninth embodiment described above, in a system whereinan engine output increasing control for increasing the engine output isexecuted without depending on the driver's accelerator operation at thetime of performing ETC cooperation down-shift on the basis of thedriver's intention of deceleration, an output increase control quantity(target throttle angle) is set in such a manner that an engine torquecorresponding to a desired engine speed change rate is developed duringthe engine output increasing control. Therefore, the engine torque canbe increased by only an amount corresponding to an inertia torque ofmembers (e.g., engine and torque converter) whose rotations are requiredto increase in a down-shift, and thus an output increase quantity(target throttle angle) free of excess or deficiency can always be set.Besides, it is possible to solve the foregoing various problems of theprior art.

Further, in this ninth embodiment, a response delay of the requiredthrottle angle change quantity dTAO is compensated while taking intoaccount a response delay in the period after output of the targetthrottle angle tangleat to the electronic throttle system until actualincrease or decrease of the intake air quantity with a consequentincrease or decrease of the engine output, and the target throttle angletangleat is set. Therefore, a transient excess or deficiency of thethrottle opening quantity can be corrected and it is possible to enhancethe accuracy of the engine output increasing control.

Tenth Embodiment

In the above ninth embodiment the required torque Te is obtained bymultiplying the engine speed change rate dNe/dt by the engine-sideinertia Ie. But in a tenth embodiment of the present inventionillustrated in FIGS. 48 and 49, the required torque Te is calculatedtaking both vehicle body deceleration (vehicle body acceleration) andthe gradient of a running road surface into account.

A target throttle angle calculation routine of FIG. 48 is executed inthis tenth embodiment. Once this routine is started, first in Step 2401,a vehicle speed Vsp detected by a vehicle speed sensor (not shown) and athrottle angle TA detected by the throttle angle sensor 18 are inputted,then in the next Step 2402 a vehicle body acceleration a (n) iscalculated by the following equation:A(n)={Vsp(n)−Vsp(n−1)}/Δt

In the above equation, Vsp (n) stands for a vehicle speed of this time,Vsp (n−1) stands for a vehicle speed of last time, and Δt stands for asampling cycle of the vehicle speed Vsp.

Thereafter, the processing flow advances to Step 2403, in which agradient δi (i=1, 2, 3, . . . ) of a running road surface relative tothe vehicle body acceleration a(n) and the throttle angle TA isdetermined using a road surface gradient map of FIG. 49. The roadsurface gradient map of FIG. 49 is set in such a manner that the higherthe vehicle body acceleration a (n), the smaller the road surfacegradient δi (δ1<δ2<δ3<. . . ). At a down gradient, the value of δi takesa negative value. The processing of this Step 2403 plays a role as roadsurface gradient determining means recited in the appended claims.

Then, in the next Step 2404, a required torque Te is calculated by thefollowing equation using the road surface gradient δi:Te=Ie×[Ne0×{(gr2+k·δ1)/gr1}/Tt]gr1: gear ratio before shift

-   -   gr2: gear ratio after shift    -   Tr: target shift time    -   Ie: engine-side inertia    -   Ne0: engine speed at time t0    -   k: constant

By the above equation the required torque Te is corrected in accordancewith the road surface gradient δi. More particularly, the requiredtorque Te corrected so as to decrease at an up gradient and increase ata down gradient.

In the case where the road surface gradient δi is not detected, therequired torque Te may be calculated by the following equation using avehicle body acceleration (a):Te=Ie×[Ne0×{(gr2+k·a)/gr1}/Tt]

By the above equation, a required torque Te corrected in accordance withthe vehicle body acceleration (a) is calculated.

Thereafter, the processing flow advances to Step 2405, in which, by thesame method as in the ninth embodiment (FIG. 46), a map for calculationof a required throttle angle change quantity dTAO with both engine speedNe and required torque Te as parameters is retrieved and a requiredthrottle angle change quantity dTAO corresponding to the present enginespeed Ne and required torque Te is calculated.

Then, the processing flow advances to Step 2406, in which the requiredthrottle angle change quantity dTAO is subjected to a response delaycompensation processing while taking into account a response delay inthe period after output of the target throttle angle tangleat to theelectronic throttle system until actual increase or decrease of theintake air quantity with a consequent increase or decrease of the engineoutput, to obtain a required throttle angle change quantity dTAO′ as aresponse delay-compensated value. Subsequently, the processing flowadvances to Step 2407, in which the required throttle angle changequantity after the response delay compensation is added to the targetthrottle angle tangleat of last time to determine a target throttleangle tangleat of this time. Other routines are the same as in the ninthembodiment.

According to this tenth embodiment described above, during the engineoutput increasing control, a road surface gradient δi is determined andthe required torque is corrected so as to decrease at an up gradient andincrease at a down gradient, therefore, even when the vehicle speedchanges due to a road surface gradient, it is possible to correct anexcess or deficiency of the output increase control quantity against adeviation of a predicted engine speed value after shift from a valuecalculated from a mechanical gear ratio which deviation occurs due tothe aforesaid change in vehicle speed.

Eleventh Embodiment

According to an eleventh embodiment of the present invention illustratedin FIGS. 51A, 51B to 55, in the case of a down-shift (“manualdown-shift” hereinafter) which occurs upon operation of the shift leveror switch by the driver, in the case of a down-shift (“auto down-shift”hereinafter) which occurs upon deceleration of the vehicle body oroperation of the brakes, and also in the case of a down-shift (“coastdown-shift” hereinafter) which occurs in accordance with a shiftschedule preset by a shift line, there is performed an engine outputincreasing control and a target throttle angle in the engine outputincreasing control is changed among the manual down-shift, autodown-shift and coast down-shift. In this eleventh embodiment, the targetthrottle angle in the engine output increasing control is set so as tosatisfy the relation of a target throttle angle for manual down-shift>atarget throttle angle for auto down-shift>a target throttle angle forcoast down-shift.

In this eleventh embodiment, since the ETC cooperation down-shiftcontrol changes according to the type of a power OFF down-shift, notonly a shift type determination routine of FIG. 54 and a shifting oilpressure control routine of FIG. 55 are executed, but also a targetthrottle angle calculation routine of FIG. 50 is executed. Processingcontents of these routines will be described below.

Shift Type Determination

Once the shift type determination routine of FIG. 54 is started, firstin Step 2111 it is determined whether the present shift command is anup-shift command or a down-shift command. If it is determined that thepresent shift command is an up-shift command, the processing flowadvances to Step 2112, in which it is determined whether the state ofload applied to the automatic transmission 51 is power ON (a state inwhich the automatic transmission 51 is driven from the engine 11 side)or power OFF (a state in which the automatic transmission 51 is drivenfrom the driving wheels side). Then, in accordance with the result ofthis determination it is determined to which of power ON up-shift (Step2118) and power OFF up-shift (Step 2119) the shift type according to thepresent shift command corresponds.

On the other hand, if it is determined in Step 2111 that the presentshift command is a down-shift command, the processing flow advances toStep 2113, in which it is determined whether the state of load appliedto the automatic transmission 51 is power ON or power OFF. If the stateof the load is determined to be power OFF, it is determined whether thedown-shift in question is a manual down-shift based on the driver'soperation of the shift lever 16. If the down-shift in question isdetermined to be the manual down-shift, the processing flow advances toStep 2116, in which it is determined whether an ETC cooperationdown-shift execution condition exists or not, for example, in order toensure controllability, it is determined whether the temperature ofworking oil lies in a temperature region in which the reproducibility ofresponse to an oil pressure command value is high. As a result, if it isdetermined the ETC cooperation down-shift execution condition exists,the processing flow advances to Step 2117, in which First ETCCooperation Down-Shift Execution Flag xEtc1 is set ON. Thereafter, theprocessing flow advances to Step 2121, in which it is determined thatthe present shift type is ETC cooperation down-shift.

If it is determined in Step 2115 that the present shift type is not amanual down-shift, the processing flow advances to Step 2123, in whichit is determined whether the present shift type is an auto down-shift ornot. If the answer is affirmative, the processing flow advances to Step2124, in which in the same manner as in Step 2116 it is determinedwhether the ETC cooperation down-shift execution condition exists ornot. As a result, if it is determined that the ETC cooperationdown-shift execution condition exists, the processing flow advances toStep 2125, in which Second ETC Cooperation Down-Shift Execution FlagxEtc2 is set ON. Then, the processing flow advances to Step 2121, inwhich it is determined that the present shift type is ETC cooperationdown-shift.

On the other hand, if it is determined in Step 2123 that the presentshift type is not an auto down-shift, or if it is determined in eitherStep 2116 or 2124 that the ETC cooperation down-shift executioncondition does not exist, the processing flow advances to Step 2122, inwhich it is determined that the present shift type is a power OFFdown-shift.

If power ON is determined in Step 2113, the processing flow advances toStep 2114 for distinguishing between power ON based on ETC cooperationdown-shift control (engine output increasing control) and power ON basedon depression of the accelerator pedal 26. In Step 2114 it is determinedwhether ETC Cooperation Down-Shift Execution Flag xEtc1 or xEtc2 is setON or not. If the answer is affirmative, the processing flow advances toStep 2121, in which it is determined that the present shift type is ETCcooperation down-shift. If ETC Cooperation Down-Shift Execution FlagxEtc is set OFF, the processing flow advances to Step 2120, in which itis determined that the present shift type is power ON down-shift.

Shifting Oil Pressure Control

The shifting oil pressure control routine of FIG. 55 is executed whenthe shift type is ETC cooperation down-shift. Once this routine isstarted, first in Step 2131 the releasing clutch oil pressure controlroutine of FIG. 11 is executed to control the oil pressure of areleasing clutch, then in Step 2132 the engaging clutch oil pressurecontrol routine of FIG. 12 is executed to control the oil pressure of anengaging clutch.

Thereafter, the processing flow advances to Step 2133, in which whetherthe down-shift has been completed or not is determined on the basis ofwhether Control Stage Flag1 and Flag2 are equal to 4 and 5,respectively. Upon completion of the down-shift, the processing flowadvances to step 2134, in which both Control Stage Flag1 and Flag2 arereset to an initial value “0” and all of other Flags xEtc1, xEtc2,xEtcTSt, xEtcFSt, xEtcTEd and xEtcFEd are reset to “OFF” to terminatethis routine.

Target Throttle Angle Calculation

Once the target throttle angle calculation routine of FIG. 50 isstarted, first in Step 2501, whether the present shift type is a manualdown-shift or not is determined on the basis of whether First Down-ShiftDetermination Flag xEtc1 is 1 or not. If the answer is affirmative, theprocessing flow advances to Step 2503, in which target throttle anglesetting maps for manual down-shift shown in FIGS. 51A and 51B areretrieved and a target throttle angle in the manual down-shift is set inaccordance with the present input shaft rotational speed Nt and coolingwater temperature.

On the other hand, if the answer in Step 2501 is negative, theprocessing flow advances to Step 2502,in which whether the present shifttype is an auto down-shift or not is determined on the basis of whetherSecond Down-Shift Determination Flag xEtc1 is 1 or not. If the answer isaffirmative, the processing flow advances to Step 2504, in which targetthrottle angle setting maps for auto down-shift shown in FIGS. 52A and52B are retrieved and a target throttle angle in the auto down-shift isset in accordance with the present input shaft rotational speed Nt andcooling water temperature.

If the answers in Steps 2501 and 2502 are both negative, the processingflow advances to Step 2505, in which target throttle angle setting mapsfor coast-down shift shown in FIGS. 53A and 53B are retrieved and atarget throttle angle in the coast down-shift is set in accordance withthe present input shaft rotational speed Nt and cooling watertemperature.

This eleventh embodiment described above is advantageous in that thetarget throttle angle can be changed according to the type of adown-shift and therefore can be set so as to afford a better feelingwith respect to the shift shock and the shift time. Besides, sincetarget throttle angles in various down-shifts are set in such a relationof magnitude as manual down-shift>auto down-shift>coast down-shift,there is obtained a shift time shortening and shift shock diminishingeffect against a manual down-shift which clearly reflects the driver'sintention of shift and an auto down-shift which is conductedautomatically in accordance with operation performed by the driver.Moreover, in a coat down-shift which occurs in coasting deceleration orslow deceleration, the down-shift can be carried out without generationof noise caused by a sudden increase of the engine speed or withoutdeterioration of fuel economy caused by an increase of fuel consumptionin this control.

In this eleventh embodiment, since the target throttle angle settingmaps for coast down-shift shown in FIGS. 53A and 53B contain all zero,the engine output increasing control is not performed in the coastdown-shift, but small values may be set in the same maps, allowing theengine output increasing control to be performed to a slight extent inthe coast down-shift.

Twelfth Embodiment

In a twelfth embodiment of the present invention illustrated in FIG. 56,a target engine sped Ner is set so that a desired engine speed or enginespeed change rate is reached in an engine output increasing control, andthe throttle angle is feedback-controlled.

More specifically, in an engine output increasing control, a targetthrottle angle is calculated by PID control so that a deviation δNe(=Ner−Ne) between a target engine speed Ner and an actual engine speedNe becomes smaller.Target throttle angle=kp×δNe+kd×{δNe(n)−δNe(n−1)}+ki×ΣδNe(n)

In the above equation, kp stands for a proportional gain, kd stands fora differential gain, and ki stands for an integral gain.

By outputting a signal of the target throttle angle to outputted to themotor driver in the electronic throttle system to actuate the throttlevalve 15 and thereby control the intake air quantity, whereby thethrottle angle is feedback-controlled so as to diminish the deviationδNe between the target engine speed Ner and the actual engine speed Ne.

Also in this twelfth embodiment described above, at the time ofperforming a down-shift on the basis of the driver's intention ofdeceleration, it is possible to execute an engine output increasingcontrol in a proper amount according to vehicle operating conditions.

The present invention is not limited to the above embodiments, but maybe constructed as follows for example.

-   (1) In a system including road shape determining means for    determining a running road shape (e.g., curving of a road or a road    surface gradient) for example on the basis of information provided    from a navigation system and road shape down-shift execution means    for performing a down-shift on the basis of the result of the    determination made by the road shape determining means, the engine    output increasing control according to the present invention may be    performed when the down-shift is performed by the road shape    down-shift execution means. By so doing, even when a down-shift is    executed automatically in accordance with the shape of a road, not    only the shift time can be shortened, but also the shift shock can    be diminished.-   (2) Even in the case of a down-shift based on the driver's intention    of deceleration, the engine output increasing control according to    the present invention may be performed only when the deceleration of    the vehicle body is a predetermined value or more. By so doing, even    in the case of a down-shift based on the driver's intention of    deceleration, if the deceleration of the vehicle body is small, it    may be determined that the engine output increasing control is not    necessary, and the execution of the same control may be omitted.

1. A controller for an automatic transmission wherein oil pressuresacting on a plurality of frictional engaging elements are individuallycontrolled by oil pressure control means to selectively switch thefrictional engaging elements between engagement and release, resultingin a switching from one shift range to another in a shift mechanism, thecontroller comprising: engine output increasing control means forperforming an engine output increasing control to increase an engineoutput without depending on a driver's accelerator operation when theshift mechanism is down-shifted on the basis of the driver's intentionof deceleration, the engine output increasing control means setting anoutput increase control quantity in such a manner that an engine torquecorresponding to a desired engine speed change rate is produced duringthe engine output increasing control.
 2. A controller for an automatictransmission according to claim 1, wherein the engine output increasingcontrol means sets the output increase control quantity on the basis ofboth a change in gear ratio caused by the shift and a shift time duringthe engine output increasing control.
 3. A controller for an automatictransmission according to claim 1, wherein on the basis of decelerationof a vehicle body during the engine output increasing control the engineoutput increasing control means corrects the output increase controlquantity so as to decrease the output during deceleration and increasethe output during acceleration.
 4. A controller for an automatictransmission according to claim 1, further comprising road surfacegradient determining means for determining a gradient of a vehiclerunning road surface, and wherein on the basis of a road surfacegradient determined by the road surface gradient determining means inthe engine output increasing control the engine output increasingcontrol means corrects the output increase control quantity so as todecrease the output in the case of an up gradient and increase theoutput in the case of a down gradient.
 5. A controller for an automatictransmission according to claim 1, wherein the engine output increasingcontrol means sets the output increase control quantity in considerationof a response delay after issuance of a command value for the outputincrease control quantity until actual increase or decrease of theengine output.
 6. A controller for an automatic transmission accordingto claim 1, wherein the engine output increasing control means sets atarget engine speed so as to afford the desired engine speed or enginespeed change rate during the engine output increasing control, andfeedback-controls the output increase control quantity.
 7. A controllerfor an automatic transmission according to claim 1, further comprisingintake air quantity detecting means for detecting the amount of intakeair introduced into the engine, and wherein the engine output increasingcontrol means increases the intake air quantity during the engine outputincreasing control and corrects an increase quantity of the intake airquantity on the basis of the intake air quantity detected by the intakeair quantity detecting means.
 8. A controller for an automatictransmission according to claim 1, wherein, in a down-shift involvingexecution of the engine output increasing control, as compared with adown-shift not involving execution of the engine output increasingcontrol, the engine output increasing control means promotes a decreaseof a working oil pressure in a frictional engaging. element controlledfor release and/or promotes an increase of a working oil pressure in africtional engaging element controlled for engagement.
 9. A controllerfor an automatic transmission according to claim 1, wherein the engineoutput increasing control means performs the engine output increasingcontrol when shifting is made forcibly to an engine brake-acting shiftrange by a down-shift which occurs with operation of brakes by thedriver.
 10. A controller for an automatic transmission according toclaim 1, wherein the engine output increasing control means performs theengine output increasing control in the case of a down-shift based onthe driver's intention of deceleration and when a vehicle bodydeceleration is not smaller than a predetermined value.
 11. A controllerfor an automatic transmission according to claim 1, further comprisingroad shape determining means for determining a road shape of a vehiclerunning road, and road shape down-sift execution means for executing adown-shift on the basis of the result of the determination made by theroad shape determining means, wherein the engine output increasingcontrol means performs the engine output increasing control when thedown-shift is executed by the road shape down-shift execution means. 12.A controller for an automatic transmission according to claim 1,wherein, in the case of a manual down-shift representing a down-shiftwhich occurs upon operation of a shift lever or a switch by the driver,or in the case of an auto down-shift representing a down-shift whichoccurs upon deceleration of a vehicle body or operation of brakes, or inthe case of a coast down-shift representing a down-shift which occurs inaccordance with a shift schedule preset by a shift line, the engineoutput increasing control means executes the engine output increasingcontrol and changes an engine output increase quantity or a target valuethereof among the manual down-shift, the auto down-shift and the coastdown-shift.
 13. A controller for an automatic transmission according toclaim 12, wherein the engine output increasing control means makescontrol so that the manual down-shift or the auto down-shift becomeslarger in the engine output increase quantity or the target valuethereof than the coast down-shift.